History of Boos

Boos are among the more commonly appearing enemy species of the Super Mario franchise. Though they first appear in Super Mario Bros. 3, Boos most prominently appear in the Luigi's Mansion series. In spinoff series, Boos have had a variety of roles, such as being an item in the Mario Kart series or obstacles in certain minigames of the Mario Party series. Sometimes, a Boo has appeared as a playable character, such as in the Mario Tennis series, and the Nintendo 64 version of Mario Tennis is the first time a Boo was made a playable character.

Super Mario series

Super Mario Bros. 3 / Super Mario Advance 4: Super Mario Bros. 3

Mario encounters a "Boo" Diddly in World 8-1.

Artwork of a "Boo" Diddly from Super Mario Bros. 3

Boos first appear in Super Mario Bros. 3 and return in its Game Boy Advance version. Here, they are referred to as "Boo" Diddlys, a pun on the name of the late rockstar Bo Diddley. However, future games refer to them only as Boos. They make their first appearance in World 2-Fortress. The "Boo" Diddly shields its face if Mario or Luigi looks at it, but it starts to chase Mario or Luigi, faster than in succeeding games, if they look away. "Boo" Diddlys are unable to be defeated unless the two are equipped with a Hammer Suit, Koopa shell, or Starman. The game also has Stretches, which are "Boo" Diddlys with very long bodies that live in the fortresses throughout the Mushroom World. In the original, depending on the level's palette, "Boo" Diddlys have either a dark-blue or dark-red outline.

Super Mario World / Super Mario World: Super Mario Advance 2

In Super Mario World and its enhanced port Super Mario World: Super Mario Advance 2, "Boo" Diddlys are now called "Boo" Buddies (though they were still called "Boo" Diddlys earlier in development) and they reside in the many Ghost Houses in the game. These "Boo" Buddies retain their usual pattern of attack from Super Mario Bros. 3 and sometimes make faces at Mario or Luigi. However, they are somewhat slower and less accurate than in Super Mario Bros. 3. This game also introduces many new "Boo" Buddy variations, such as the Boo Buddy Block, Boo Buddy Snake, Boo Crew, Circling Boo Buddies, Eeries, and Disappearing Boo Buddies. It also introduces a giant version of the "Boo" Buddy, the Big Boo. One Ghost House contains a secret boss, a special Big Boo. The only way to defeat a "Boo" Buddy is with Super Stars or with Grab Blocks when it is visible. Unlike later games, the "Boo" Buddies in this game seem to have multiple tails. The groups of "Boo" Buddies also have different facial expressions, while individual "Boo" Buddies change theirs for a brief second if they are stared at long enough.

Super Mario Land 2: 6 Golden Coins

Boos appear in Super Mario Land 2: 6 Golden Coins. Compared to other games, they move in a slower, wave-like pattern toward Mario. Boos in this game are found in the Pumpkin Zone. A thrown Green Shell can defeat it. A variant named Ghost Goombas also appears in this game.

Super Mario 64 / Super Mario 64 DS

A Boo in Super Mario 64

A Boo in Super Mario 64 DS

Boos (also called Baby Boos) make a starring appearance in the course Big Boo's Haunt in Super Mario 64. A group of Boos can be found in the Mushroom Castle's courtyard (eight of which are holding Red Coins in the DS version). After collecting twelve Power Stars, Mario is able to enter Big Boo's Haunt by going into the little cage (also called a "carousel") that a Big Boo drops. He also battles an extra-large Big Boo three times here. Additionally, when Mario looks at the Boos, they attempt to hide by becoming partially transparent, but if Mario is not looking at them, they chase him. If they hit him, he loses two wedges of health. In the translucent Boo, the player can see a Yellow Coin or a Blue Coin.

To defeat the Boos, a punch or kick from behind or the side is needed. They can also be defeated with a Pound the Ground attack while Mario is not looking at them. When defeated, they give a Blue Coin, but the ones in the courtyard give a normal coin instead. When a Boo is defeated in the first mission, Go on a Ghost Hunt, it says, "Ghosts...don't...DIE! Heh, heh, heh! Can you get out of here...alive?" In addition, a Boo appears in the hallway of the Mushroom Castle after twelve Stars are collected.

In Super Mario 64 DS, Boos use their current design introduced in Mario Party 4. Additionally, eight Stars are needed to spawn a small Boo in the hallway, who holds a Red Coin. After fifteen Stars are collected, the small Boo is replaced by a Big Boo, which then allows Mario, Luigi, or Wario to enter Big Boo's Haunt. If the sixth mission is selected and the player is not Luigi, one particular Boo wears Luigi's cap. In the haunt, Mario can find a Luigi painting, which takes him to the Big Boo Battle level on the balcony. After defeating King Boo within, Mario gains the key to the room in which Luigi is imprisoned and proceeds to free him. In the English version of the game, King Boo is also referred to as "Big Boo," resulting in three separate entities with that name. Yoshi cannot defeat Boos in this game. Ground-pounding yields no results, and eating them simply causes Yoshi to spit them back out. Boos that end up being eaten will say, "You...can't...EAT...ghosts! Eee hee hee!" Mario, Luigi, or Wario can hit them with Pound the Ground attacks. Additionally, Luigi can also use the spin jump from his backward somersault to defeat Boos.

Super Mario Bros. Deluxe

The Boos from
Super Mario Bros. Deluxe,
arranged by speed

While Boos do not appear in the original Super Mario Bros., Boos appear in Super Mario Bros. Deluxe as competitor characters in the "You VS. Boo" mode. The goal is to reach the flagpole before the Boo. After defeating Boo within a certain time frame, it flies away, and a green Boo replaces it. After that Boo is defeated, a red Boo takes its place, and finally, a Black Boo with a yellow outline appears. Each new Boo gets progressively faster than the one before it, meaning the plain White Boo is the slowest, while the Black Boo is the fastest; the Black Boo copies the player's best time, which makes it the hardest to defeat. Unlike other games, these Boos do not hurt the player on contact.

Super Mario Sunshine

A Boo from Super Mario Sunshine

Boos return in Super Mario Sunshine, terrorizing the residents of Hotel Delfino. In this game, they move around in slow, swooping motions and do not care if Mario looks at them. They tend to go in Mario's general direction while turning invisible (aside from some distortion), but spraying them with FLUDD causes them to slowly become visible again. These Boos can be defeated by being jumped on, making Super Mario Sunshine the only game outside of the Super Mario RPGs where jumping can defeat them. Boos in this game can also be eaten by Yoshi. They also disguise themselves as Yellow Coins and Blue Coins, which only spin to face Mario instead of spinning at a constant pace. Boos can also disguise themselves as Shadow Mario while the real Shadow Mario runs from Mario, though they appear lighter than Shadow Mario, lack the magic brush, and do not have the theme music. When Mario approaches a disguised Boo, it laughs and bumps into him, though if it is sprayed beforehand it will start behaving like the other Boos. Like the other enemies, Boo's design is changed for this game, with drooping eyelids, blue circles surrounding their black pupils, and long, coiled tails. This is due to the fact that they are made from graffiti.

The Boos in this game are led by King Boo. Mario finds him in the basement of the hotel's Casino, and he has to battle him. He can defeat him by throwing a Chili Pepper at him and then throwing another piece of fruit at him. Mario has to do this three times before King Boo is defeated. Pink Boos also appear and can be turned into a platform if sprayed by FLUDD. Also appearing inside the hotel are a new species, known as Sleepy Boos. These large Boos mostly appear to block passages. FLUDD's water does not affect them; they can be removed only by being eaten by Yoshi.

New Super Mario Bros.

Boos also appear in New Super Mario Bros. They are found mainly in Ghost Houses scattered throughout the game, as well as World 8-1. They appear like they usually do, shy, and they act the same as in Super Mario Bros. 3. They can only be defeated with a Shell, a Starman, a Mega Mushroom, or a Blue Shell. The game also introduces the Balloon Boo, which are normal Boos who can suck up air, and become much bigger. Broozer, the boxing ghost, first appears in this game as well. An icon of 2 Boos covers the progress map in Ghost Houses.

Super Mario Galaxy

Mario looking at a Boo in Super Mario Galaxy

Boos make an appearance in Super Mario Galaxy and can be found in the Ghostly Galaxy, the Bigmouth Galaxy, the Deep Dark Galaxy, and the Sand Spiral Galaxy. Boos act the same way that they did in previous games, such as hiding by turning transparent when Mario looks at them and then following Mario when he looks away. Boos can be defeated only when they are brought under a ray of light (including the Toad Brigade captain's helmet and the light emitted from shells while in the water) or by Rainbow Mario touching them. The spin attack, however, can throw a Boo around Mario, knocking it off course temporarily or into a light. Boos can also be found underwater in the Bigmouth Galaxy where they attack just by swimming back and forth, similar to Cheep Cheeps. In Deep Dark Galaxy, in the secret mission, there is a large Boo that has a Power Star in it.

Boo Mario also appears in this game. Mario has the same body as the other Boos, but retains his face when in his Boo form. He also wears his trademark cap on his head. If a Boo spots Mario while he is a Boo, it develops an attraction for him and follows him. If a Boo hits Mario, Mario loses the power-up but does not lose any health.

An Atomic Boo makes an appearance in this game, as well as a racing one named the Spooky Speedster. This game also introduces a new kind of Boo, called the Bomb Boo; it is similar to a normal Boo, but it is black with yellow eyes and can be grabbed by its tongue if Mario uses his spin attack on it.

Captain Toad also indirectly suggests that Boos eat people, as he worried that Luigi might have been eaten by ghosts.

New Super Mario Bros. Wii

A Boo chasing Mario in New Super Mario Bros. Wii

Boos reappear in New Super Mario Bros. Wii in Ghost Houses throughout the game. They behave the same way as they did in New Super Mario Bros. and are invincible, unless the player has a Star power-up. Big Boos also reappear along with Broozers. Circling Boo Buddies can also be found in a small number of Ghost Houses in the game. Despite their concept art, they appear with a blue glow as opposed to plain white in this game, giving off a more spectral appearance. In the level selection screen, a single Boo will be watching Mario and will taunt Mario as he enters. If Mario gets tossed out, the Boo will laugh. However, once the level is beaten, the Boo will cover its face for the rest of the game.

Super Mario Galaxy 2

Boos in the Boo Moon Galaxy in Super Mario Galaxy 2

Boos reappear in the game Super Mario Galaxy 2. They behave the same way they did in its predecessor. They are found in haunted levels such as Haunty Halls Galaxy and Boo Moon Galaxy. The underwater Boos from the predecessor also appear in this game, in the Battle Belt Galaxy and Slimy Spring Galaxy. Bomb Boos also reappear. As well, two new variants have been introduced: Octoboos, which resemble ghostly Octoombas; and Mega Boos, which are larger than Big Boos.

Super Mario 3D Land

A Boo chasing Fire Mario in Super Mario 3D Land

Boos later appear in Super Mario 3D Land. In the game, they retain their normal battle strategy, which is chasing Mario when he looks away while sticking their tongue out. Boos in this game also momentarily disappear when hit with Fire Mario's fireballs and Tanooki Mario's tail whips. Boos also laugh in their original phonic from Super Mario 64. Some Boos have striped tails; these are called Tail Boos. They act like normal Boos, but when they stop moving when Mario looks at them, they will swing their tails once, which can damage Mario. Big Boos also appear during the game. Another species of Boo is also introduced, called Peepas. They do not move freely like normal Boos and instead move around a set position, and do not halt when Mario looks at them, as in Super Mario Galaxy.

New Super Mario Bros. 2

Boos pushing the walls in New Super Mario Bros. 2

Boos, along with Big Boos, return in New Super Mario Bros. 2, with the same appearance and behavior as in New Super Mario Bros. Wii, except they turn completely red when Mario faces them. They can be found in Ghost Houses along with other ghost enemies such as Peepas and the new Boohemoth. All of these varieties, save for Boohemoth, can be defeated with a Star or Gold Flower. Boos can also be turned Gold Boos with a Gold Ring. When gold, Boos float away from Mario, leaving a trail of coins behind them.

There are also Boos that push walls in a Ghost House, namely World 4's Ghost House. Here they push the wall either left or right and they do not stop when Mario looks at them.

New Super Mario Bros. U

Artwork from New Super Mario Bros. U

Boos, Big Boos, and Circling Boo Buddies appear in the Wii U title New Super Mario Bros. U. Their behavior is the same as that of past installments. Boos also have their own Enemy Course in the haunted area of Soda Jungle, where a group of Boos appear in an area with various Donut Blocks, and defeating them must be done using the Super Star located inside a Flying ? Block. They can also be defeated with a Baby Yoshi.

Super Mario 3D World / Super Mario 3D World + Bowser's Fury

Boos in Super Mario 3D World

Boos appear in Super Mario 3D World and its Nintendo Switch port Super Mario 3D World + Bowser's Fury, along with Peepas and Big Boos. They retain the same strategy from Super Mario 3D Land and utter the same laugh from Super Mario 64. They appear to be a bit more transparent than in previous mainstream Super Mario games and give out a blueish glow like in the New Super Mario Bros. games, as well as a reddish glow and even steam when Mario faces them.

Super Mario Maker subseries

Super Mario Bros. styled Boos from Super Mario Maker

Boos reappear in Super Mario Maker, Super Mario Maker for Nintendo 3DS, and Super Mario Maker 2 as enemies. They function the same as previous games. They have been given new sprites for the Super Mario Bros. style. In the Course Maker, they can be placed as enemies and can be shaken to turn into Boo Buddies. They can also be dragged onto a platform, turning them into Stretches. Like many enemies, they can be enlarged by a Super Mushroom and be given wings. The former will turn it into a Big Boo, and the latter will make them move much faster. They can be placed in Warp Pipes, Bill Blasters, Blocks, and tracks. In addition, adding Wings to a Boo Buddy makes the Boo Buddy move in and out. If a Boo is placed in a Koopa Clown Car, the Koopa Clown Car stops and closes its eyes when it is looked at, and sneaks up on the player when looking away.

Super Mario Run

A Boo holding a Color Coin from Super Mario Run

Boos appear in Super Mario Run in Ghost House levels. When Mario looks at them, they cover their eyes and float up and down. They attack Mario by quickly following behind him. Mario can defeat them by jumping over them while they are giving chase by using a Backflip Block or a Wall Jump. In some levels, pressing the pink P Switch defeats Boos on-screen. They can drop Keys, Coins, or Color coins after they are defeated, and the object they contain inside of them can slightly be seen through them before they are defeated. In Dark and Stormy, Boos are defeated when a lightning strike occurs. Stretches also appear in the game.

Super Mario Bros. Wonder

King Boo with several other Boos in Super Mario Bros. Wonder

Boos reappear as enemies in Super Mario Bros. Wonder. Here, they look similar to their older 2D artwork, although they still stick their tongues out. Boos behave the same way as in other games, and can be defeated by luring them into light like in the 3D Super Mario games. Additionally, King Boo returns during a Wonder Effect.

DIC cartoons

The Adventures of Super Mario Bros. 3

A Boo in The Adventures of Super Mario Bros. 3 episode "Reign Storm".

Boos make infrequent appearances in The Adventures of Super Mario Bros. 3 television series, which depicts them as having a somewhat menacing appearance. They are depicted with red eyes and yellow teeth. Like in the game the show is based on, Boos work for Bowser and often aid him in causing trouble. An example of this is seen in the episode "Reign Storm," in which Bowser has several Boos terrorize the new Mushroom Shopping Mall. In this episode, they are referred to as "Boo Diddlys."

Super Mario World television series

Yoshi encountering a Boo in the Super Mario World television series episode "The Night Before Cave Christmas".

In Super Mario World, Boos, who are completely redesigned, appear in the episodes "Ghosts 'R' Us," in which a gang of Boos, as well as a Big Boo, appears to chase Yoshi through Wizenheimer's haunted house; "The Night Before Cave Christmas," in which they scare Yoshi away; and "The Yoshi Shuffle," in which several Boos appear in the audience during the episode. They are never referred to by name, instead simply being referred to as "ghosts". They more closely resemble their in-game sprite.

Nintendo Adventure Books

Boos chasing Luigi on the front cover of Koopa Capers, the fourth of the Nintendo Adventure Books

In Koopa Capers, a Boo confronts Luigi if he decides to simply look through a keyhole in a fortress door, instead of barging through it. If Luigi decides to run away from it immediately, he will successfully escape, but if he decides to stand his ground, the Boo will chase him onto some floating blocks after he dodges its attack. Making a beeline for the door after mounting the blocks will allow the Boo to catch Luigi, but doing evasive techniques will allow him to escape it. When he begins his descent into the Magma Pit, Luigi will hear a Boo behind him, which causes him to pick up the pace, and escape it.

Illustrations of a Boo are used in puzzles in Dinosaur Dilemma and Flown the Koopa, though none appear in the actual stories.

Super Mario World: Mario to Yoshi no Bōken Land

Boos swarming Luigi, Yoshi, and Mario from Super Mario World: Mario to Yoshi no Bōken Land

In the interactive OVA Super Mario World: Mario to Yoshi no Bōken Land, Boos appear in a Ghost House that Mario, Luigi, and Yoshi are passing through. A Boo starts following Luigi, who is in the back, but every time he turns around, it disappears. Finally, he quickly does a double take, and turns just in time to see it re-materialize. He panics and Boos start swarming the group. Mario grabs a candle and lights it, which repels the Boos, and one drops a key they need to progress.

Yoshi franchise

Yoshi

A Boo Buddy from Yoshi

Boo Buddies make an appearance as one of the six falling objects in Yoshi. Boo Buddy's sprite in this game is similar to its sprite from Super Mario World.

Yoshi's Cookie

In Yoshi's Cookie, Boos return as enemies to Yoshi. Though in this game, they are depicted as one of Yoshi's "opponents". They are among the easy opponents, the others being Goomba, Cheep Cheep, Paratroopa, and Spiny. Eeries also appear, as well as the similarly-named Fishin' Boos.

Yoshi's Safari

A Big Boo from Yoshi's Safari

Boos (misnamed "Big Boo" in the English manual) appear as enemies in Yoshi's Safari. Their first and only appearance throughout the game is in Ghost Mansion, a level in the Dark Realm. Unlike most enemies in the game that can be shot with the Super Scope to be defeated, shooting a Boo stops it in its tracks. While stunned, Yoshi can then run into it to defeat it. Defeating a Boo adds 500 points to the player's score (1,000 in Hard Mode), the highest amount of points earned from regular enemies. A Big Boo serves as the boss for the level.

Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3

Boos in Super Mario World 2: Yoshi's Island have smaller eyes and thinner eyebrows compared to its contemporary depictions, as well as bottom fangs. This design is later used in the first three installments in the Paper Mario series.

The first appearance of Boos in the Yoshi's Island series is Super Mario World 2: Yoshi's Island and its enhanced Game Boy Advance port. They first appear in World 2, alongside several other ghastly creatures. The only way to defeat Boos is by looking away and then make an egg bounce off a wall after it is thrown, hitting the ghost in the face. Kamek the Magikoopa turns one Big Boo into Bigger Boo, which serves as a mini boss and grows in size every time he is hit by an egg. The main boss of World 2 is also a Boo-like creature, Roger the Potted Ghost, who was a normal flower pot until Kamek made him giant and transformed it into a living creature. The game also features the Boo Balloon, who are balloons made to look like Boos that yield items when they pop, as well as Boo Man Bluff, a blindfolded Boo that relies on noise to detect the player.

Yoshi's Story

A Boo in Yoshi's Story

Boos appear in Yoshi's Story in Stage 6-3: Ghost Castle. They do not act differently, although they are slightly bigger. The Ghost Castle is also home to other Boo species: namely, the Block Boo, Blindfold Boo, and Little Boos. Another variant, the Jelly Ghost, inhabits the jelly of Stage 2-3: Jelly Pipe and Stage 2-4: Torrential Maze. The Big & Little Boo family also appears in Jelly Pipe.

The normal Boo is mistakenly called a Big Boo in the Nintendo Power guide.

Yoshi Topsy-Turvy

Boos in Yoshi Topsy-Turvy only appear in mission 6-7, with Big Boos being more common. They follow the same tactics as normal, and are given their laugh from preceding releases.

Yoshi's Island DS

Two Boos from Yoshi's Island DS

Boos appear in Yoshi's Island DS, where they behave identically as in Super Mario World 2: Yoshi's Island and can be defeated in the same way as before. There is also a Boo-like midboss in Hector the Reflector.

Yoshi's New Island

Boos return in Yoshi's New Island, retaining their behavior in previous games. They first appear in Beware the Boo Brigade retain their laugh from Super Mario 64.

Mario Kart series

Super Mario Kart

Boos made their first appearance in the Mario Kart series in Super Mario Kart as items exclusive to "2 Player" mode, under the name "Ghosts". When the player uses it, they will become transparent temporarily (19 seconds), while the "Ghost" steals the opposing player's item, if available. They also appear as background elements in the three Ghost Valley courses, where they laugh when the player drives by.

Mario Kart 64

Boos (named Ghost Bonuses on one occasion) return as a usable item in Mario Kart 64. They can be obtained if the player is in the top two positions. When activated, the Boo selects a racer with the best item in reach, steals the item, and gives it to the player that released it. At the same time, the player obtains total invisibility and invincibility for a short period of time. While invisible, the player can pass the items, the course obstacles, and the other racers more easily by simply going through them. If no other players possess items, the Boo will return empty-handed. Boos also appear in Banshee Boardwalk and the image of one appears in neon lights in Rainbow Road, both as background elements.

Mario Kart: Super Circuit

A Boo from Mario Kart: Super Circuit

Boos holding candles as Yoshi passes by

Boos attacking Toad

Boos on Boo Lake (top) and Broken Pier (bottom)

Boos appear as items again in Mario Kart: Super Circuit. When activated, they can also slow down the leading racer. Starting in this game, if a CPU racer uses a Boo, it can also steal items from the player and make the player lose Coins. The transparency effect lasts for five seconds.

Boos, also referred to as "ghosts", also appear in two new courses, Boo Lake and Broken Pier. At Boo Lake, Boos hold candles that guide the player through the track. On Broken Pier, they attack the players and take their Coins.

Mario Kart: Double Dash!!

Boos do not appear as items in Mario Kart: Double Dash!!. However, Boos, as well as the Boolossus' gold frame portrait, appear in the Luigi's Mansion battle course. Also, King Boo makes his Mario Kart debut as a playable character alongside his partner, Petey Piranha.

Mario Kart Arcade GP subseries

Boo item from Mario Kart Arcade GP DX

Boos appear as items in the arcade game, Mario Kart Arcade GP. A Boo appears as a basic item. It causes whoever is hit by it to slow down temporarily. There is also a new item called the Triple Boo. Boos reappear in Mario Kart Arcade GP 2 and Mario Kart Arcade GP DX, functioning identically as before.

Mario Kart DS

Boo item from Mario Kart DS

In Mario Kart DS, Boos reappear as items (with the name of Boo Hoo in the European instruction manual). They can be obtained if the player is anywhere from 3rd to 7th place. This time, they no longer slow down the leading racer, nor do they steal the best item in reach. Instead, they just steal the nearest racer's item. However, while using the Boo item in this game, the player will not be slowed down while driving on off-road surfaces, allowing various shortcuts to be made. Some pictures of Boos from the game, Luigi's Mansion, appear in the Luigi's Mansion race course. N64 Banshee Boardwalk reappears as a race, along with the Boos. They do not do anything that affects the racer; they just laugh when a racer drives by.

Mario Kart Wii

Boos from the track Ghost Valley 2 in Mario Kart Wii

Much like in Mario Kart: Double Dash!!, Boos do not appear as items in Mario Kart Wii, but King Boo appears as a playable character. However, Boos do appear in a returning course, SNES Ghost Valley 2. Like their original appearance in the track, Boos only laugh when racers drive by, but they eventually disappear. Boo also makes a cameo in Bowser's Castle. At the end of the track, Boo's Mario Party 7 artwork can be seen along with Dry Bones' artwork.

Mario Kart 7

Boos seen in the Luigi's Mansion track from Mario Kart 7

In Mario Kart 7, Boos appear in the returning track, Luigi's Mansion, in place of the portrait ghosts. They will pop out of their paintings when the drivers race by them. They also appear as spectators on Toad Circuit and N64 Luigi Raceway.

Mario Kart 8 / Mario Kart 8 Deluxe

A Boo inside a Hammer Knight from Mario Kart 8

Luigi holding a Boo from Mario Kart 8 Deluxe

In Mario Kart 8 and Mario Kart 8 Deluxe, Boos appear as obstacles in Twisted Mansion. If aimed correctly, the players can land on the Boos floating around near the gliding section. They also possess Hammer Knights near the end of the track. These same Boos can also be seen floating around on GCN Luigi's Mansion in Mario Kart 8 Deluxe and GBA Boo Lake in the Mario Kart 8 Deluxe – Booster Course Pass, the latter where they replace the candle Boos from the original iteration.

Mario Kart 8 Deluxe reintroduces Boos as items. Boos immediately steal an item from a random racer in front of the user, and invincible or other invisible players are not immune; the Boo will bring back a Mushroom if there is nothing to steal. The Boo is visible, both when it steals an item and when it gives the stolen item to the user. It takes a couple more seconds to deliver the item back to the user, however. Only one Boo can be in play at a time; once it brings back an item, another can appear in Item Boxes again, even while another player is still invisible. Due to the way deployed items work, a Boo is able to steal any timed or multiple usage item, except for a Crazy Eight, Piranha Plant, or Bullet Bill already in use. Stealing such an item will always give the user a fresh version of the item. Unlike Mario Kart DS, the player can no longer cut through off-road sections while invisible.

King Boo also returns as a playable character in Mario Kart 8 Deluxe.

Mario Kart Tour

A wooden cutout of two Boos in Mario Kart Tour

Boos reappear in Mario Kart Tour in the courses SNES Ghost Valley 1, SNES Ghost Valley 2, GBA Boo Lake, DS Luigi's Mansion, and RMX Ghost Valley 1, where they act the same as they did on those courses in previous games. Wooden cutouts of Boos also appear in the Ghost Valley courses and DS Luigi's Mansion.

In every Halloween Tour since 2020, the 2021 Autumn Tour and the Battle Tour, Jack-o'-lanterns are scattered throughout the courses, some of which had Boo faces. Additionally, King Boo is once again a playable character. A glider known as the Boo Masks also appears in the game as Peach (Yukata)'s signature glider, who also has a Boo ribbon.

Mario Kart Live: Home Circuit

Boos reappear in Mario Kart Live: Home Circuit in Boo Fortress, frightening racers who hit them.

Super Mario Adventures

In Super Mario Adventures, a horde of Boos appear to attack Mario and Luigi when they are tricked into a haunted house by Bowser and the Koopalings. Mario and Luigi become trapped by the Boos and a Big Boo, who are held at bay by the bros staring at them in the face. Eventually, nearing exhaustion, Mario races to a nearby room, dragging Luigi while being chased by the Boos. Upon barging into this room, the Boos and Big Boo find Mario dressed as a psychiatrist with Luigi as his nurse. After some talking, Mario and Luigi manage to reform the Boos and the Big Boo, while learning they were bullied in their youth (which is why they act so nasty to everyone). These Boos and their Big Boo leader were last seen happily waving goodbye to Mario, Luigi and Yoshi as they left the haunted house, which the Boos led them out of.

Boos also make an appearance at Toadstool's wedding.

Super Mario Bros. film

While Boos do not physically appear in the 1993 Super Mario Bros. film, a sign saying "NOW PLAYING BOO DIDLEY"^[sic] can be seen in Dinohattan.

Mario Bros. series

Mario Bros.

Boos make an appearance in the Super Mario All-Stars remake of Mario Bros., where they replace the fireballs in the Battle Game found in the main menu of Super Mario Bros. 3.

Mario Clash

Artwork of a Big Boo from Mario Clash

Boos (misnamed "Big Boo" in the English manual) make appearances in the Virtual Boy game, Mario Clash, where they are among the target enemies. In this game, Mario is able to attack a Boo from the side. Boos can become transparent by becoming dark like the screen, which causes them to become invulnerable, with shells simply passing through. For some reason, the English manual also refers to the Boos using feminine pronouns, similar to Cheep Cheep in the original Super Mario Bros.

Hotel Mario

A Boo from Hotel Mario

Boos also appear in the game Hotel Mario under the name Boo Buddies. Some Boos behave similarly as in the Super Mario series: attacking Mario when his back is turned and hiding behind their arms when looked at. However, while Mario is in an elevator, these Boos wander in diagonal patterns. There are some other Boos that are normally transparent and wander in a similar manner, regardless of where Mario looks, but occasionally become fully visible and quickly charge at him.

Mario's Picross

Boos in Mario's Picross appear in one of the pictures in the "Early Picross" stage in level 6C. The other character that appears in the "Early Picross" stage is Mario, who appears in level 6H. Like their first appearance, Super Mario Bros. 3, they appear under the name Boo Diddly.

Super Mario RPG: Legend of the Seven Stars

Artwork of a Boo from Super Mario RPG: Legend of the Seven Stars

Boos return during the events of Super Mario RPG: Legend of the Seven Stars and its Nintendo Switch remake. In the original game, the English translation erroneously calls them "The Big Boo", whereas the remake simply calls them Boos. In the Japanese version, they are, in fact, referred to as Teresa as they are in other games. These Boos, like other Boos that appear in previous games, hide behind their arms when stared at. However, some Boos teleport around the room, attempting to scare Mario and his friends. Boos live in Kero Sewers along with many other ghouls, including Hobgoblins and Shadows. Often, these three undead monsters will assist each other in battle. Boos have no physical defense, making them extremely weak enemies (for reference, a Goomba is the weakest enemy encountered and it has three defense points). However, Boos make up for their lack of defense with high evasion, meaning that most attacks against Boos will miss. In battle, Boos command powerful lightning magic, including the attacks Lightning Orb and Bolt. Boos also know the special attack Scream, which cuts a party member's attack and defense in half. When not using magic, Boos approach one of Mario's party members and make a face, damaging that character. In this game, there is also a stronger Boo variation called High Boos, which are the same size as their normal counterparts but have blue tongues, similar to the first appearance of King Boo. The only true appearance of a Big Boo in this game is the one used in Bowser's Terrorize attack. One Boo lives in Monstro Town as part of the Three Musty Fears.

Super Mario-kun

Boo as it appears in Super Mario-kun

Lady Bow as seen on the cover of Super Mario-kun issue 25

Boos make appearances in some of the Super Mario-kun comics. A Boo appears on the cover of the sixteenth issue. This issue is based on Super Mario 64. Alongside it, Eyerok, a Bob-omb, and Bowser can be seen. Throughout the comic, they appear, too. Their role in the comic is similar to their role in the game, where they are enemies to Mario and attempt to attack him. Lady Bow, a notable Boo, appears in a couple of the Paper Mario-based issues. These issues are 25 and 27. Lady Bow appears on the cover of the twenty-fifth issue along with many of Mario's other partners, including Goombario, Kooper, Eldstar, and Twink. Besides appearing on the cover, she appears throughout the comic. Her role in the comic mimics her role in the game. Lady Bow reappears on the cover of the twenty-seventh issue and in the comic. Like in issue 25, Lady Bow's role in the comic is similar to her appearance in the game, where she helps Mario. In a Super Mario Galaxy-based issue, Boo Mario appears on the cover along with more of Mario's transformations.

Game & Watch Gallery series

Game & Watch Gallery 2

Boos (called "Boo Buddies") appear in the Modern version of Vermin in Game & Watch Gallery 2. When Yoshi looks in the general direction of them, they refuse to move. When Yoshi looks away, they move towards the eggs. They only appear in groups of two or just one.

Game & Watch Gallery 4

A Boo appears in the Modern versions of Donkey Kong 3, Mario's Cement Factory, and Boxing in Game & Watch Gallery 4. In Donkey Kong 3, if Mario or Donkey Kong turns his back, it will slowly come closer to the player that it is closer to. If it gets close enough, the Boo will either scare Donkey Kong and award the player points (single-player mode only) or scare Mario and give the player a miss. In Mario's Cement Factory, a Boo will fly into the two containers on the second floor, clogging them up. The player does not receive any points for removing the Boo. In Boxing, one of the opponents Luigi faces is a Big Boo, who uses a regular Boo as a boxing glove.

Mario Party series

Boo has been a major character in the Mario Party series, from being a thief for hire to being a playable character.

Mario Party

Players cutting out Boos in Crazy Cutter from Mario Party

Boos make minor appearances in Mario Party. Their voices can be mimicked by one of the items: the Talking Parrot. Boos also appear in each of the game's board maps, excluding Peach's Birthday Cake. On the boards, they steal Coins or Stars from opponents, and they are willing to steal a few coins for free from any player, although they will steal the number of coins at random. They also ask for 50 coins to steal a Star. If the player tells Boo that they do not want to steal anything, Boo will say "Don't feel so guilty. Ha ha ha!" Additionally, after the Luigi's Engine Room board is completed, a Boo, Koopa, and a Toad, along with the two runner-ups, surround the victor and congratulate them. Boos also appear in several mini-games, including Pedal Power and Running of the Bulb, and as one of the shapes the player can cut in the minigame, Crazy Cutter.

Mario Party 2

Boos make several appearances in Mario Party 2. In it, they steal Coins or Stars as they did in the first game. However, Boo charges 5 coins to steal coins instead of a free steal; and steals much more than in the first game. Additionally, an item called the Boo Bell appears. When a player obtains it, they can ring for a Boo to come. The Boo that comes to the player's side is asked to steal Coins or Stars, depending on how much the player can afford. If the Boo is sent to steal Coins from an opponent, the opponent can fight it off by pressing the A button quickly. Additionally, the Boo can only steal a maximum of 30 coins or a maximum of one Star.

A Boo also appears in the battle minigame Day at the Races along with the other racers; Whomp, Thwomp, and Bob-omb. The Boo can disappear and then reappear in a further spot on the racetrack. However, it gets its face stuck in the ground sometimes, causing it to stop for a short period of time. In Skateboard Scamper, the players must use their skateboards to escape a pursuing Boo.

Mario Party 3

Boos in Curtain Call from Mario Party 3

Boos also appear in Mario Party 3. Like in their previous appearances, they are not major characters in the game. They are among the Duel Partners in the Duel Mode Partners. It is Yoshi's default partner, and when an opponent attacks, Boo can counterattack for equal damage, unless it is defeated by a Thwomp. Boo will only counterattack a Chain Chomp if it is directly in front of the Chomp when it attacks. Boo's attack is two, its stamina is one, and its salary is three coins.

Boos also appear in the unlockable party board, Waluigi's Island. Whenever a player runs into a Boo, it shows them two paths. One of the paths is rigged. If the player chooses the rigged path, they are sent back to the start. If they choose the correct path, they continue on the board. In addition, Boos appear on all of the other boards, Chilly Waters, Deep Bloober Sea, Spiny Desert, Woody Woods, and Creepy Cavern, serving the same function as in the previous games. On the board map, a picture of them can be seen next to a grave. They also return with the Boo Bell. Boos are also in the minigames Curtain Call, Stacked Deck, Three Door Monty, and Crowd Cover. Two portraits of a Boo can also be seen in Locked Out.

Mario Party 4

The sorcerer Boo from Mario Party 4

In Mario Party 4, a Boo plays a major role as the host for Boo's Haunted Bash. This is the first game where Boos use their modern design. This Boo wears a wizard's hat and cape, and like the other hosts in the game, it is the character to reward the player with a Star. Multiple Boos also appear on this board as background characters. A particularly surly one controls the Item Shop. Another one owns the Mystery Train, but it only gives out rides to the Boneyard if a Red Boo is not in its presence. Two side games involving Boos require a Mini Mushroom. One of them has the player pressing one of the keys of the Horn of Plenty to get one of three randomly chosen items. The second one has the character on a piano. They have to press the correct key at the right time until the end of the side game to get a certain amount of Coins. A question mark space activates a Boo clock. If three people land on them, Big Boo will appear. Big Boo is basically an upgraded version of the Boo House; it targets all players instead of one. The caped Boo is also the fourth host of the Reversal of Fortune, who oversees what is given.

Boos also appear on every other board in the game, stealing coins and Stars for the player at a shop called the Boo House in the same manner as Boos' previous appearances in the Mario Party series.

Also, a Boo is an unlockable, playable character in the Extra minigame, Beach Volley Folley.

In Long Claw of the Law, a Boo is one of the possible characters that needs to be collected.

Mario Party 5

Boo from Mario Party 5 playing Coney Island

Mario Party 5 marks the first game in the Mario Party series where Boo is a playable character in Party Mode. It is one of the new characters, the others being Koopa Kid and Toad. Boo's partner in the game is Koopa Kid. Since Boo is playable, it does not make any major background appearances. Its previous role on the boards is now fulfilled by Chain Chomp.

Mario Party 6

Boo, along with some Red Boos, from Mario Party 6

A Boo reappears as a playable character in Mario Party 6. In the game, there is also an orb called Boo Away Orb, which protects the player from a Red Boo. Red Boos also appear in the minigame Boo'd Off the Stage and Boonanza!. Red Boos also appear on two boards, Towering Treetop and Castaway Bay where they let players steal coins and stars from others at night, similar to the Boo House in Mario Party 4. This game also marks the third appearance of Red Boos in the Mario Party series.

Mario Party Advance

“Ee hee hee! It's ghastly news!”

—Boo, Mario Party Advance

Boos in the Horror Condo in Mario Party Advance

Boos appear in Mario Party Advance as supporting characters. Four of them haunt Boo Cemetery, although one of them is soon revealed to be an impostor. As a part of their mission, True-Blue Boo, the player is asked to identify and reveal the impostor along with their golden Boo statue in exchange for the Predictotron.

When the player visits the cemetery, they are greeted by the four Boos. They mention a crime when Shroomlock appears to assist them. At the mention of a theft, the Boos become worried and ask them to help track down their golden Boo statue, which they consider a symbol of their friendship. At this time, they appear to realize there are four Boos rather than their usual three, assuming one of them is an impostor. The player is asked to select the Boo with a slightly different moveset and rhythm, revealed to be Koopa Kid if correct. Although he gets away, the statue is left behind. As thanks for this, the remaining Boos award the player the Predictotron. According to the information preceding the credits, the Boos now regularly haunt Horror Condo.

Boos also appear in a few minigames, including Boo-Bye. In this minigame, regular Boos appear alongside Red Boos and Blue Boos. They also appear in Spooky Spike, in which one Boo serves volleyballs to the player, Floor It!, in which Boos are one of the possible passengers that must be brought to their respective floor, and Porta-Gust, in which the player can suck up Boos into a vacuum.

Mario Party 7

Artwork of Boo and Dry Bones from Mario Party 7, also found at Bowser's Castle in Mario Kart Wii.

Mario Party 7 marks the third Mario Party game where Boo is playable. It also marks Dry Bones' first playable appearance, who is Boo's partner throughout the game. Red Boos appear in the game, too. Red Boos appear in a few minigames such as Ghost in the Hall. In this minigame, Red Boos try to scare the players. Oddly, the Red Boos also try to scare Boo, if Boo is one of the characters. Boo shares the same special orb with Dry Bones, the Magic Orb. It allows them to double their dice roll during the next two turns and turns them invisible, making them immune to traps.

Mario Party 8

Boo from Mario Party 8

In Mario Party 8, Boo is a playable character for the fourth time in the Mario Party series. Boo's partner is Dry Bones, again. Red Boos appear in some minigames such as Boo-ting Gallery. Mario Party 8 also marks the first appearance of King Boo, who is the board host of King Boo's Haunted Hideaway. In order to get a Star, the player must find the room King Boo is hiding in and give him ten coins. There are three rooms, two of which contain a trap hole. If the player finds one of these rooms, several Red Boos will throw them in, forcing the player to start back at the beginning. When the player gets a Star, King Boo will rearrange the mansion's rooms. Red Boos appear as owners of the item shops.

Mario Party DS

Boo is not a playable character in Mario Party DS and plays no part in board play, but appears as an unlockable figure. They also appear in the minigames Boo Tag, and Peek-a-Boo. In Boo Tag, a Boo tags a player. The tagged player must try to get rid of the Boo by running into another player. The player that spent the least amount of time with the Boo wins. In Peek-a-Boo, the players must find the wanted Boo. A lot of different Boos appear in hats and different colors such as red, blue, green and yellow. Several of the wanted Boo appear, and once they are all gone, the game is over. The team that won the most Boos wins.

Mario Party 9

A Boo in Mario Party 9

Boo does not return as a playable character in Mario Party 9, however King Boo is the boss of Boo's Horror Castle. Normal Boos also appear on the board. When the player passes a Boo portrait, a Boo will emerge and chase after the player. These Boos will move three spaces after each turn, and if a Boo catches up to the players (or vice versa), the current captain will lose half of all of their Mini Stars.

During King Boo's Puzzle Attack, whenever King Boo's health is depleted halfway, he sends Boos to attack the player. If the player's cursor touches a Boo, they are temporarily stunned. King Boo only sends one Boo at a time.

Mario Party: Island Tour

Boo from Mario Party: Island Tour

Boo returns as a playable character in Mario Party: Island Tour. This is the fifth time that Boo is playable, the first time it is playable on a handheld Mario Party game, and it is the first character in the series to be removed as a playable character in a main installment of the series and then return in a later installment.

Mario Party 10

Boss minigame King Boo's Tricky Tiles from Mario Party 10

Boo reappears in Mario Party 10 as a non-playable character. Whenever the player reaches a certain spot in the board Haunted Trail, Boo appears and steals five Mini Stars from a specific player for an indefinite number of turns. Boo will continue to harass the player until passed off to another player via a Boo Space or driven towards a Streetlight. Boos also appear in the minigame Boo Burglars, as enemies the players must examine, and appear as a balloon in the minigame Balloon Blast Bash. Several Boos also make cameos in the Luigi Board.

Mario Party: Star Rush

Boo's Block Party from Mario Party: Star Rush

In Mario Party: Star Rush Boo has a special mode called Boo's Block Party. Players can participate in a single-player endless mode for a high score or compete in a one-on-one versus mode. When a player uses the Boo amiibo in Boo's Block Party, four Boos appear in the background: two on the top screen and two on the Touch Screen. If a player taps the Boo amiibo in the Mario Shuffle mode, the player can use Boo in that mode. They also appear in the Haunted Hallways and House of Boos minigames.

Mario Party: The Top 100

In Mario Party: The Top 100, Boo appears in minigames such as Slot Trot from Mario Party 6 and Jigsaw Jumble from Mario Party 9. However, in Minigame Match, Boo appears as an item via Boo Bell.

Super Mario Party

Boo returns as a playable character in Super Mario Party, which is its sixth playable appearance in the Mario Party series. Because of its status as a playable character, Lakitu takes its role as the one who steals coins or Stars from the earlier Mario Party installments. Its Boo Dice Block consists of two of each -2 coins, 5, and 7.

Mario Party Superstars

Boos in Mario Party Superstars

Boo returns as a non-playable character in Mario Party Superstars, behaving like it does in the first three Mario Party games. Boos also return in Roll Call and Crazy Cutters.

Mario Golf series

Toadstool Tour character
Boo
Drive	208 yards
Star Drive	253 yards
Trajectory	Slice
Height	3/5
Impact	13/21
Star Impact	09/21
Control	10/21
Spin	08/21

Boos make a couple of appearances in the Mario Golf series. In Mario Golf and in Mario Golf: Toadstool Tour a Boo appears in the top right corner of the screen to indicate the speed and direction of the wind.

Mario Golf

Artwork of Boo Valley from Mario Golf

In Mario Golf for the Nintendo 64, Boos show where the wind blows by facing its direction in relation to the camera angle. They do not appear if there is no wind. Hole 2 of Mario's Star is designed after Boos. Also, Boos appear in the artwork for one of the courses, Boo Valley. Boo's name appears on the scorecard sometimes.

Mario Golf: Toadstool Tour

Boo getting a Birdie from Mario Golf: Toadstool Tour

Boo is one of the unlockable characters in Mario Golf: Toadstool Tour, the others being Bowser Jr., Shadow Mario, and Petey Piranha; it is the only one to have not debuted in Super Mario Sunshine and is the only one that appears in the opening clip. In Bowser Badlands, Boos affect the trajectory of balls hit through them. Boos once again reprise their role of showing the wind direction, but they have another role; if a player delays in starting their swing, then two Boos carry a sign and float across the screen. These signs describe basic gameplay tips, but some are taunts to the player.

Mario Golf: World Tour

Boo getting a Hole-in-One in Mario Golf: World Tour

Boo returns in Mario Golf: World Tour as a playable character, this time being available from the start. Boos also appear in Hole 4 of Bowser's Castle floating in the sky alongside King Boo. For this installment, a "blowing cloud" is used instead of a Boo to indicate wind speed and direction.

Mario Golf: Super Rush

A Boo appears as a Spin character in Mario Golf: Super Rush, where the standard version is available normally and a version with a visor available as an unlockable for playing in Ranked Match. Boo has the highest Spin stat in the game. Boo's Special Shot is Mischief Twister, in which multiple Boos appear and merge into Boo's golf ball before the swing for the shot is made. If it lands near other balls, Boos will come out and haunt them. Balls that are haunted cause the trajectory in the shot gauge to be curved, resulting in the shot not being able to travel in a straight line unless a special shot is used. Boo's Special Dash is the Carousel Dash, which causes multiple Boos to circle around Boo and carry Boo forward. Because Boo levitates, they are not penalized by travelling across any body of water or lava, although travelling on them will deplete the stamina gauge, and if it fully depletes, the character will travel back to the surface before contacting water or lava (this trait is shared with Rosalina).

In Golf Adventure mode, Boo appears as part of the rookie class with the player’s Mii, Toadette, and Chargin’ Chuck.

Mario Tennis series

Mario Tennis (Nintendo 64)

Boo from Mario Tennis (Nintendo 64)

Boo appears as a default character in Mario Tennis for the Nintendo 64, marking his first playable role. He is classified as a tricky character, the only other character of this class being Paratroopa.

Mario Tennis (Game Boy Color)

A Boo in the minigame Boo Blast from Mario Tennis (Game Boy Color)

A Boo appears in the Boo Blast minigame in Mario Tennis for the Game Boy Color. They can also be seen in the audience at Peach's Castle.

Mario Power Tennis

Artwork of Boo for Mario Power Tennis

Boo also appears in Mario Power Tennis where he is a playable character. This marks the first game where Boos are given a new voice. When he wins a championship, Mario and Luigi would come out with the trophy and Boo would be missing. They look around and the trophy would start to float. Boo then appears under it to Luigi's relief as Mario laughs in amusement. The Mario Bros. themselves are then surrounded and levitated by multiple other Boos as the main Boo flies up to the screen and holds the trophy. Boo's taunt is to wave his racket while laughing. Boo's offensive power shot is the Boo Blast and defensive power shot is the Boo Brigade Return.

Mario Tennis Open

Boo in Mario Tennis Open

Boo reappears in Mario Tennis Open, where he is again a playable and starting participant. He is classified as a Tricky characters alongside Bowser Jr. and White Yoshi.

Mario Tennis: Ultra Smash

Boo in Mario Tennis: Ultra Smash

Boo appears in Mario Tennis: Ultra Smash as a default playable character. He is once again a Tricky character.

Mario Tennis Aces

Boo from Mario Tennis Aces

Boo returns as a playable character in Mario Tennis Aces. Like in previous Mario Tennis games, Boo is classified as a Tricky character. His Trick Shots are Roundabout and Through It All, while his Special Shot is Illusion. Boo also has unlockable alternate costumes, coming in the form of visors, that can be unlocked by playing the "Boo Hunt" co-op challenge. In this challenge, the player must hit Boos at the other side of the court to get coins. The visors came in Blue, Green, and Purple and require 2,500 coins, 10,000 coins and 20,000 coins respectively.

Paper Mario series

Boos have appeared in every game in the Paper Mario series, where they are usually found in ghost houses, like in the other Super Mario games. In the first three Paper Mario games, the Boos appear with a design similar to Bigger Boo from Super Mario World 2: Yoshi's Island. In the latter three games, they use their modern appearance from Mario Party 4 and onward.

Paper Mario

“I want to hear people shriek and watch them run away yelling! That's what makes Boos happy.”

—Boo, Paper Mario

Boos in Boo's Mansion from Paper Mario

Two kinds of Boos from Paper Mario

Boos appear in Paper Mario as friendly but tricky characters. White Boos live in Boo's Mansion, and tan Boos live at Gusty Gulch. Their leader is Lady Bow, who lives in Boo's Mansion along with Bootler.

At first, Boos were being eaten by Tubba Blubba. Some Boos tried attacking the monster to save their friends, but they failed because of Tubba Blubba's "Invincibility". Seeking help from Mario, they captured Skolar, the Star Spirit Mario was trying to save, in order to have Mario help them.

In the game, when Mario arrives at Boo's Mansion, Bootler tells him to get to the third floor. The Boos have prepared some puzzles for him under the order of Lady Bow to test him. One puzzle is for Boos to form a rotary circle, throw an item several times and ask Mario to guess who is holding the item. The first time he opens a door a big Boo appears on the screen. In the eastern room of the second floor Boos holding a Record play this trick. In the western room of the second floor, a Boo is guarding a chest box with a Weight in it. Mario plays the Record to lure the Boo away and uses the Weight on the droplight of the mansion to open the western door on the first floor. Boos in the basement hide in a big chest box in the basement. When Mario opens the chest box, they play the puzzle with Super Boots. After Mario gets them, he is able to get Boo's Portrait with which he is able to get to the third floor. There, Lady Bow asks Mario to help the Boos to defeat Tubba Blubba as a condition to free Skolar, and joins Mario's party to assist him.

A Boo by the name of Igor also has a shop in the basement, but he will not sell until after Lady Bow joins the party.

In addition, a Boo appears after Mario gets the Super Boots, and tells him how to get the Star Pieces underground. Additionally, some Boos are flying in the sky who can be seen out of the windows. When Mario is about to set off, two white Boos appear to open the gate to Gusty Gulch under the command of Bow.

In Gusty Gulch, upon Tubba Blubba's arrival, the Boos hide except for Stanley, who is too late and gets caught and eaten by Tubba Blubba.

In the basement of Tubba Blubba's Castle, a brown Boo tells Mario not to fight Tubba Blubba until he finds his weak point. According to his word, he sneaked into the castle to look for the weak point. After Mario gets Yakkey, some tan Boos appear in front of Tubba Blubba's Castle and, seeing Mario and Bow get out and Tubba Blubba chasing, help the team by blocking the door.

After Tubba Blubba is defeated, the Boos he has eaten are saved, and Bootler releases Skolar as promised. Boos rejoice, and the background music in Boo's Mansion is replaced with a cheerful one. The Boos at Gusty Gulch write Lady Bow an admiration letter, which the player can read at the Toad Town Post Office. They also begin to talk about a female Boo called Victoria.

After Mario defeats Bowser, two Boos come to Peach's Castle to see the party, one white and one brown. The white one says he comes to see Lady Bow in her finery. He thinks that Bow is prettier than Princess Peach. The brown one says that he is going to have a wedding ceremony after the party. In the end-of-game parade, three white Boos along with Bootler are carrying Tubba Blubba's body.

Paper Mario: The Thousand-Year Door

Boos return in Paper Mario: The Thousand-Year Door as friendly characters as well as enemies for the first time in the series. Some Boos such as Lahla and Peeka in Rogueport can be seen running shops and various casino games. Enemy Boos are found in Creepy Steeple and levels 21-29 of the Pit of 100 Trials. When Mario first enters the steeple there is only one Boo in the room who says that he misses his friends. He will let Mario through only one door (blocking him from using any other doors), where he finds a chest. When he opens it, 200 Boos fly out. The last Boo asks Mario "How many Boos came out of that chest?" If Mario answers correctly the Boo will give him an Ultra Shroom. If Mario is wrong the Boo will give him one coin. Upon returning to the main room, the first Boo is still there. He asks if Mario is going to be mean to him. If Mario answers "No", a bunch of Boos (the same ones from the treasure chest) will start flying around the main room, attempting to swarm Mario. If successful, they will throw Mario out of the Steeple, exactly like the Sentinels in Tubba Blubba's Castle. If Mario Spin Attacks them several times, they merge into an Atomic Boo. Once the Atomic Boo is defeated (releasing a Lucky Start badge), Mario can fight Boos in other parts of the Steeple. Even before defeating the Atomic Boo, Boos can still be found, but only when accompanying Swoopers.

The original Creepy Steeple Boo sends an e-mail to Mario that thanks him for freeing his friends, despite the fact that they attacked him. He signs the letter "The Creepy Steeple Boo". More Boos can be found in the Pit of 100 Trials. In this game, Boos attack by becoming invisible and getting close to Mario or the partner, then becoming visible and making a glare at them, causing 3 damage. However, if Mario or his allies gets lucky in battle, the Boo who tried to attack Mario and his partner will be tired out. The game also introduces a more powerful sub-species, the Dark Boo, which can be found in Poshley Sanctum.

Boos can also appear as members of the audience, where they can throw items onto the stage and randomly turn a character in the battle invisible for one turn.

Field Tattle

Outside of battle, Goombella can use Tattle only on a Boo found in the foyer of Creepy Steeple after Mario releases the 200 Boos.

• "That's a Boo. You think it's one of the Boos from that box?"

Super Paper Mario

Boos in the minigame Mansion Patrol in the Flipside Arcade from Super Paper Mario

Boo's Catch Card

Boos return as enemies in Super Paper Mario. In this game, they turn invisible if Mario looks at them, but they turn visible and chase him if he is not looking at them, similar to their behavior in Super Mario 64. To defeat them, the player must approach them from the back and then attack them. Additionally, the Flipside Arcade houses a Boo themed shooting game, Mansion Patrol. This game has the player shooting Boos, including Dark Boos and occasionally Atomic Boos, to score points. A Toad frequently appears to give power-ups, as long as the player saves him from his Boo captor. Lady Bow also makes three cameos in this game.

Paper Mario: Sticker Star

Boos reappear in Paper Mario: Sticker Star. They only appear in World 4-3: The Enigmansion. Mario must use the Book of Sealing, given by a Toad, to seal away every Boo that has escaped. In battle, Boos can make themselves disappear and can slap Mario or they can go up to Mario and scare him by making a scary face. They are able to make Mario dizzy in this game with their scare attack preventing him from using any of his defensive/dodging stickers. The attack is determined by the sound the Boo makes when it disappears.

Among the normal Boos, there is one golden Boo that drops several Coins after Mario defeats it, which can be found in the safe. This Boo attacks exactly like the normal ones. Another notable Boo is one that is crumpled, which is found in a trash can. In battle, it only has 1 HP and cannot attack. Additionally, a group of eighty-two Boos called a Boo Stack also appears. Once all the Boos get returned to the book and it is placed in its rightful spot, Kamek appears and turns all the captured Boos into the mini boss, Big Boo. After defeating the mini-boss, the Boos are put to rest once again and the mansion is restored to its former state. Boos can no longer be fought at this point.

Paper Mario: Color Splash

A Boo 10-Stack from Paper Mario: Color Splash

Boos return in Paper Mario: Color Splash as enemies who can be fought within the parallel world at Vortex Island, Lighthouse Island and Fortune Island. By the time they are first encountered, Mario can instantly defeat them with a hammer First Strike without entering a battle. In battle, they attack by either hitting Mario or scaring him. They can disappear while in battle, causing all attacks to miss until they reappear. Outside of battle, if one is stared at too long, it will disappear, and then reappear behind Mario. A Boo appears as an NPC in Redpepper Crater, where it is in a hot spring. A Boo 10-Stack variant also appears.

Paper Mario: The Origami King

An origami Boo as seen in Paper Mario: The Origami King

A Paper Macho Boo

Origami Boos appear as enemies in Paper Mario: The Origami King, first encountered in the Scorching Sandpaper Desert, but only at night; after Mario has explored the Temple of Shrooms and put the sun back in the sky, they are replaced by Koopa Paratroopas. In battle, Boos will turn invisible right before Mario manipulates the arena, forcing him to memorize their positions. However, they will reveal themselves if they are hit by a Toad's thrown object or shortly before time runs out. In addition, much larger Paper Macho Boos appear in the desert at night, replaced by Paper Macho Koopa Paratroopas by day. A Paper Macho Boo is also featured as one of the seven opponents on Scuffle Island.

Luigi's Mansion series

Luigi's Mansion

Main article: List of Boos in Luigi's Mansion

A Boo in Luigi's Mansion

Luigi following a Boo in the Nintendo 3DS remake.

In Luigi's Mansion and the Nintendo 3DS remake, Boos serve under King Boo, who is the main antagonist. There are 50 Boos (51 including King Boo) which Luigi must suck up in the Poltergust 3000. Of these, 15 of them are smaller ones that make up the portrait ghost Boolossus, with King Boo as the final Boo. Unlike the other ghosts in the game, Boos will appear in a room, even when the lights are on. When Luigi attacks them, they usually run away, but occasionally twirl into him to cause damage. All of the 36 Boos, excluding King Boo and counting Boolossus as one Boo, have puns in their names. Contrary to the Super Mario series, Boos hide when Luigi's not looking at them, and they face Luigi when he finds them.

Luigi's Mansion: Dark Moon

Main article: List of Boos in Luigi's Mansion: Dark Moon

A Boo in Luigi's Mansion: Dark Moon

Boos appear in Luigi's Mansion: Dark Moon. They have names that play on "Boo" as in the first game. King Boo appears, having a similar appearance to that of his debut. They have the ability to create Spirit Balls which can make objects invisible until exposed with the Dark-Light Device. All of the regular missions in the game have a Boo in an object that is invisible, and Luigi must find it by revealing the invisible object with the Dark-Light function of the Poltergust 5000; the Boo appears after the revealed Spirit Balls have been vacuumed up. However, not all Boos are hidden in invisible objects.

To capture a Boo, Luigi must expose it with the Dark-Light, vacuum and pull on the Boo's tongue, and release it with the Button, damaging the Boo as it bounces around the room. When it reaches 0 HP, the Boo can be sucked up; it sticks onto the nozzle, and Luigi presses the Poltergust 5000 against the ground to shove it inside. When Luigi returns to the Bunker after completing a mission, any captured Boos are sent to the Boo Canister in the Vault. After all Boos in a mansion have been captured, a bonus mission is unlocked for the corresponding mansion. There are a total of 32 Boos, 33 if counting King Boo, 10 of which merge into the Big Boo fought in the Treacherous Mansion.

Luigi's Mansion 3

Main article: List of Boos in Luigi's Mansion 3

A Boo in Luigi's Mansion 3

Boos return in Luigi's Mansion 3. Like in previous entries, they have "Boo"-inspired names, and King Boo returns as the main antagonist. Every floor except the Master Suite has a Boo to capture, which appears after Luigi has obtained that floor's elevator button. The exact location of each Boo is randomized. To help find a Boo, Gooigi will begin to vibrate, corresponding with the player's controller, when next to the room with the Boo in it. There is also an item in the game known as a Boo Finder, which reveals the location of a single Boo. Once Luigi enters the room with the Boo, the music will change and he must uncover the object with the strongest vibrations, which causes the Boo to appear and seal all exits until caught. If a wrong object is uncovered, the Boo will launch a swarm of bats at Luigi and flee to a different room. Once revealed, Boos attack by either spinning towards Luigi to deduct 20 HP or by throwing a bomb at him. To capture the Boo, Luigi must expose it with the Dark-Light device, then pull on its tongue and slam it repeatedly. All Boos have 20 HP.

Super Smash Bros. series

SmashWiki article: Boo

In the Super Smash Bros. series, Boos mostly appear in the form of collectible items. In Super Smash Bros. Melee, a Boo appears as a collectible trophy. In Super Smash Bros. Brawl, there is another trophy of Boo, as well as a sticker depicting its artwork from Mario Tennis. In both Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U, Boos once again received their own collectible trophy; furthermore, Super Smash Bros. for Wii U gave one an item in Smash Tour, where using it allows the player to begin a battle while invincible. In Super Smash Bros. Ultimate, there is a Novice-class Neutral-type primary spirit of a Boo, using its artwork from New Super Mario Bros. U, and it can be enhanced to King Boo at level 99. In World of Light, the Boo spirit appears in the Dracula's Castle sub-world of the Dark Realm. The spirit battle takes place on the Mushroom Kingdom U stage, with an invisible grayscale Kirby as the puppet fighter.

Boos appear in the background of the Luigi's Mansion stage in Super Smash Bros. Brawl, Super Smash Bros. for Wii U, and Super Smash Bros. Ultimate. Here, they are very briefly seen flying out the mansion when a part of it is knocked down.

Mario & Luigi series

Mario & Luigi: Superstar Saga / Mario & Luigi: Superstar Saga + Bowser's Minions

A Boo chases the Mario Bros. in Mario & Luigi: Superstar Saga.

In Mario & Luigi: Superstar Saga, Boos are enemies that only appear in Bowser's Castle; they aid Bowletta along with the rest of the minions who believe her to be Bowser. Outside of battle, they hover around, attacking Mario and Luigi when they are not looking. However, they look away if Mario or Luigi make eye contact. The Boos also show the ability to teleport. In battle, a Boo has two attacks. For the first attack, the Boo will teleport in front of one of the brothers and attempt to bite him. For the second attack, it will fly up into the air and swoop into one of the Mario Bros., which can even prohibit the use of certain moves or items. The former attack can be countered with Mario or Luigi's hammer, whereas the latter can be dodged or countered by jumping. In either of these attacks, if the Boo makes a face, it will target Luigi, if it does not, it will target Mario. Boos are weak to Firebrand and Fire Bros. They also have low HP, but very high defense.

Boos wearing mining helmets and brandishing pickaxes also appear in levels 4 and 5 of Mysterious Mine Carts. If these Boos touch Mario, they will cause the loss of a diamond. They will slowly shrink until they disappear if the flashlight is pointed at them.

Boos appear in the main game and in Minion Quest: The Search for Bowser from Mario & Luigi: Superstar Saga + Bowser's Minions. Boos are flying troopers, and attack by ramming into enemies. Their Special Skill, Evasion Cloak, allows them to increase their evasion, depending on how filled the meter that is shown becomes. Captain Boo appears as a playable captain in the game. When a Boo appears as a captain, they are able to attack the other captain from behind, using Sneak Attack.

There are also Boo Statues which become invisible and cannot be interacted with when looked directly at. Mario and Luigi must use the Tickle move to push them while facing backward.

Mario & Luigi: Partners in Time

During the events of Mario & Luigi: Partners in Time, Boos appear in Bowser's Castle of the past. In the field, Boos attack the same way as they did in Mario & Luigi: Superstar Saga. In battle, a Boo attacks by peeking through one of its eyes; peeking with the right eye is Mario, and with the left eye, Luigi. The Boo reappears behind the corresponding bro and charges from behind; this can be avoided or countered with a jump. Boos also appear during the battle with Sunnycide. While flipped on its back, Sunnycide can summon a Boo to attack Mario or Luigi, which can be countered with a hammer. Also, when a Handfake has a Bowser sign, a Boo or a Fly Guy carries a flame from Bowser's mouth. Dark Boos are found in the Gritzy Caves.

Mario & Luigi: Bowser's Inside Story / Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey

A Boo holding a plate

A digital Boo.

Boos make a reappearance in Mario & Luigi: Bowser's Inside Story. They appear in Bowser's Castle, where they have been brainwashed by Fawful along with the rest of Bowser's minions once he took over the castle. When Bowser gets to have a feast as a reward for beating Midbus at the Fawful Theater show, three Boos serve him food cooked by Fawful himself. However, Bowser is tricked into eating too much food and ends up getting fat, which results in him getting stuck in the floor due to his weight. Boos reappear later in the game to help many of the brainwashed minions of Bowser push the Fawful statue against him. In addition, a Boo appears whenever Bowser gets a level up. The Boo (just like the Fishin' Lakitu in Mario's or Luigi's level up screen) holds the circle for getting a bonus upgrade for the stat of the player's choice.

An odd thing shown in the game is a Boo and Koopa Troopa in love with each other in Bowser's Castle. They not only love each other, but also love Fawful due to the brainwashing that was put on the minions.

Yikk, a ghost who appears in the same game at the Tower of Yikk, explains that he researches Boos. He even builds a machine to visualize Boo transparency waves before he passed away.

During the fight with Bowser Memory ML, Bowser Memory L has an attack that involves a digital Boo chasing him around. The Boo can be jumped on by either Mario or Luigi to stop the attack prematurely.

Boos return in Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey, where they additionally are found as enemies and recruitable allies in the Bowser Jr.'s Journey mode. Their special attack is Discord, which lowers the speed of enemies.

Mario & Luigi: Dream Team

While Boos themselves do not appear in Mario & Luigi: Dream Team, an item named Boo Biscuit does.

Mario & Luigi: Paper Jam

Boos appear in Mario & Luigi: Paper Jam in a minigame where the player has to save a Toad by running away from a Boo and avoiding firebars and bombs. Like in many other games, this Boo will stop if the Mario Bros. look at it, and will follow them if they look away. Boos can also be seen carrying Papercraft Boos, along with Papercraft King Boo. Their paper versions also appear as regular enemies in the haunted side of Gloomy Woods. King Boo also appears as a boss in Gloomy Woods. Boo Biscuits also return from Mario & Luigi: Dream Team.

Mario vs. Donkey Kong series

Mario vs. Donkey Kong

Boos appear in Mario vs. Donkey Kong, acting similarly to their other appearances in platforming games. They only appear in both segments of Level 4-4 and in Level 4-4+. They cannot be defeated, and if they manage to defeat Mario or the Mini-Mario, the Boo will grow and stick its tongue out.

In the game's Nintendo Switch remake, Boos are more clearly depicted with a toylike appearance. Also, in co-op play, they float towards Toad if his back is turned away, but stop moving if he looks at them.

Mini Mario & Friends: amiibo Challenge

Boos in their active and inactive states in Mini Mario & Friends: amiibo Challenge

In Mini Mario & Friends: amiibo Challenge, Boos have a toylike appearance and float in mid-air, with some moving on a straight path (vertically or horizontally) from side to side, while others staying in one place. They are invincible and, when in their active state, harmful to touch. However, they become harmless when they enter the light coming from a Candle. In this state, they are also forced to stop in place and cover their eyes, much like an actual Boo does when a character faces it in platform games, and the Minis are able to pass through them.

Boos are present in all levels of Moonlight Mansion, as well as levels Star 3 and Star 5 in the Star World.

Mario Pinball Land

A group of Boos with Big Boo in Mario Pinball Land

In Mario Pinball Land, Boos appear in certain areas in the game. Mario cannot hit them at the front because they will become transparent as Mario passes through them. If Mario hits one of the Boos on its back, the Boo disappears and it is worth 2,000 points. They occasionally will disappear and reappear to another spot in the area.

A Big Boo also appears as one of the game's bosses. He is the boss of the haunted house and can only be damaged by hitting it from behind.

Dance Dance Revolution: Mario Mix

A Boo with Mario from Dance Dance Revolution: Mario Mix

Some Boos make appearances in Dance Dance Revolution: Mario Mix in both regular and giant varieties. Their objective is to try to make Mario miss a step. If successful, they block Mario's next move. Mario is able to step on regular Boos to hold them back, but he cannot do the same to their gigantic counterparts.

Mario Baseball series

Boo prepares to bat in Mario Super Sluggers

Mini Boo being used in Mario Super Sluggers

Boo makes its first baseball appearance in Mario Superstar Baseball. It is on Wario's team as a starter. Boo is tied with Peach with its pitching, losing only to Bowser and Waluigi. Its special running and fielding move is a Super Jump. Its running and batting are weak, but its fielding is very poor. The only worse fielder in the game is Bowser.

Boo makes another appearance in Mario Super Sluggers. It is on Wario's team once again, and it can be unlocked in Wario City by finding it in between boxes and completing its challenge. Like its predecessor, Boo has the highest ranked pitch in the game, along with Peach (9/10). Despite its pitching being very high, its stamina is very poor, but its other stats range from average to low. Boo displays good chemistry with King Boo, Shy Guy, Magikoopa, and Blooper. It has bad chemistry with Mario, Luigi, Yoshi, Baby Mario, Baby Luigi, Baby Peach, and Baby Daisy.

There is a new item named Mini Boos that, when activated, turn the ball invisible for a short period of time. If used against a computer, the player stops moving until the Boos go away. If used when a special hit is in effect, the Boos do nothing.

Super Princess Peach

Boos in Super Princess Peach act like in the Super Mario series: they hide their face when Peach looks at them but attack when Peach has her back turned. However, there is an angry variety called the Mad Boo, which attacks the opposite way. They attack when Peach looks at them, and gander around for her when she looks away. Aside from Boos, Big Boos, Mad Big Boos, and Blindfold Boos are introduced as enemies, and King Boo appears as a boss.

Mario and the Incredible Rescue

Two Boos on the cover of Mario and the Incredible Rescue

Boos make an appearance in the chapter book Mario and the Incredible Rescue. The cover features two Boos. One of the Boos is from Mario Kart: Super Circuit and the other is a mirrored Boo from Luigi's Mansion. The book never uses their proper name, only referring to them generically as ghosts. Boos capture Princess Peach and take her to Bowser's Castle. Mario also sees a vision of Princess Peach being caged and surrounded by six Boos. Boos are eventually defeated by Mario at the end of the book. To defeat them, Mario casts a spell on them and sends them flying out of the castle.

Mario Hoops 3-on-3

Boo performing its Thriller Dunk

Boo appears in Mario Hoops 3-on-3 as an unlockable character of the Tricky type. Its special ability is the Thriller Dunk. Boo can be unlocked by completing the Flower Tourney on hard difficulty.

Mario Strikers Charged

Boo from Mario Strikers Charged

In Mario Strikers Charged, Boos are one of the sidekick options to the many captains. They appear with a helmet with the logo of their team captain. Boos are classified as a playmaker. The only other playmaker sidekicks are Toads. Their skillshot is Possess. The given description of the Boos is: "This ghost can fly up and down the sidelines with great speed, using precise and accurate passing to lead his team to victory. His long-distance shots are quite weak though and his hits are not very powerful. If Boo gets a chance, he can Possess the ball and score at will."

Mario & Sonic series

A sprite of a Boo from the Nintendo DS version of Mario & Sonic at the Olympic Games

In the Mario & Sonic series, Boos mainly appear in a few events, sometimes also as audience members. In the Wii version of Mario & Sonic at the Olympic Games, Boos appear as an item in Dream Race, where they temporarily follow whoever is in first place, or second if the player in the lead uses it, causing them to lose speed. It is possible for multiple Boos to follow a character at once, causing them to remain at a lower speed, but a High Speed item can remove them. In the Nintendo DS version, Boos penalize the player if they perform two consecutive fouls in the 100m, 400m or 400m Hurdles events, and in Dream Basketball, a Boo blocks one of the baskets if a Chaos Emerald is used. Both versions of Mario & Sonic at the Olympic Games include Boos as part of the audience in various events. In the Nintendo DS version of Mario & Sonic at the Olympic Winter Games, Boos are items in three events: Ski Cross Racing, where they can steal Rings and items from players ahead of the user; Extreme Snowboarding, where Boos steal items from opponents in front and deplete the energy in their trick gauge; and Ski Shooting, where Boos will simply steal an item from an opponent if they have any. In the Nintendo 3DS version of Mario & Sonic at the Rio 2016 Olympic Games, Boos appear in Archery Plus, where they carry around the targets and disappear upon being shot.

Boos appear in some of the minigames. In the Nintendo DS version of Mario & Sonic at the Olympic Games, Boos appear in two minigames: Conveyor Belt, as one of the characters needing to be sorted, and Shoot!, as one of the enemies to be hit. In Mario & Sonic at the London 2012 Olympic Games, Boos also appear in some minigames in the London Party mode, which itself has some Boos that can be spoken to play minigames and earn stickers.

King Boo talking to a Boo in The Ghostly Tower

Boos have also had some of their own collectible items. In the Wii version of Mario & Sonic at the London 2012 Olympic Games, one of the unlockable Mii outfits is a jersey featuring a Boo design. In the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games, a badge of a Boo can be obtained from the badge machine.

In Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games, a Boo first appears in the Story Mode trying to scare people away from the Tower of London with the Phantasmal Fog, and is then followed by Sonic and Tails who challenge the Boo and King Boo to an Olympic Event, with the Boos fleeing when they lose. A single Boo also appears at the opening ceremony. A Boo also appears in Mario's Defeat?!, in which it fails to bring Mario to the London Tennis Club but helps set up the match with a Goomba transformed to look like Mario, and later celebrates with the other minions when they notice that Bowser seems to be back to his usual self.

Mario Sports Mix

Boos seen in the background in Mario Sports Mix

Boos appear in Mario Sports Mix. They appear as the only members of the crowd in Luigi's Mansion circling around the court. Their appearances are in Basketball and Volleyball matches and their laughs can also be heard during the game. Mainly, they can be heard when the player gets a point.

Captain Toad: Treasure Tracker

A shy Boo in Captain Toad: Treasure Tracker

A Boo in Captain Toad: Treasure Tracker

Boos return in Captain Toad: Treasure Tracker and its Nintendo Switch and Nintendo 3DS ports, functioning the same as they did in Super Mario 3D World with a few minor tweaks. Despite still chasing the player when not watched, Boos and Big Boos can easily be destroyed with Toad's or Toadette's headlamp. Additionally, using a Double Cherry to shine two headlamps on a Boo will defeat it much faster, within a quarter of a second.

Interacting with Boos on the touch screen or with the pointer functionality will cause them to disappear until the player points away. Unlike most enemies in the game, holding the pointer on Boos for however long will not reward a coin.

Mario Sports Superstars

A Super Rare Boo card from Mario Sports Superstars

Boo appears as one of the starter captain-type characters in Mario Sports Superstars. In most sports, he is classified as a Technique type character, sharing this attribute with Peach, Daisy, and Waluigi. As such, he excels in aspects such as shot accuracy or horse control. In tennis, Boo is instead a Tricky type character, as per his appearances in the Mario Tennis series, alongside Bowser Jr. and Rosalina. His rallies have a tendency to curve, making it tricky for the opponent to predict the trajectory of his shots. In golf, Boo's default drive is 213 yards, and his shots travel medium-low in a draw trajectory.

Mario + Rabbids series

Mario + Rabbids Kingdom Battle

A Boo in Moonlight Sonata from Mario + Rabbids Kingdom Battle

Boos appear as obstacles in certain areas in Mario + Rabbids Kingdom Battle. They warp to certain areas during the turn transition between the heroes and enemies. If a Boo converges on a character, it will follow said character and force them to warp to a random spot on the battlefield along with the Boo. Additionally, one of Rabbid Mario's Melee weapons has a design based on a Boo, and in Spooky Trails, several Boos can be found ensnared by ghostly chains, as well as a Boo Balloon that was merged with a Rabbid and a phonograph, becoming the Phantom.

Mario + Rabbids Sparks of Hope

While no Boos appear in Mario + Rabbids Sparks of Hope, the laugh of one can be heard if the Spark Vampastra applies its Vamp Attack ability to Mario, and he uses his Dual Slingers to attack. In the Rayman in the Phantom Show DLC, Boos make cameos as the Spooky Trails banners from the first game.

Dr. Mario World

Artwork of Dr. Boo in Dr. Mario World

The Boo assistant was added on October 31, 2019. Its effect in stage mode is to fill the skill meter faster when yellow viruses are eliminated, where it fills more at higher levels. The percentage determines the number of points the skill meter fills, so for example at level 3, it fills 30% faster, meaning that for each yellow virus eliminated, an extra 0.3 points is added to the skill meter. In versus mode, its effect is to increase the speed the skill meter fills for both the user and their opponent, in which the amount of points required to fill the skill meter is reduced by the listed percentage. If both players use this assistant, the effect stacks. The resulting amount of points required to fill the skill meter is rounded down to the nearest round number.

A Boo was added as a doctor under the name Dr. Boo in Dr. Mario World on September 24, 2020. His skill is represented by the Boo shielding his face, after which he shows his face and tongue. In stage mode, he immediately eliminates objects in a random 2 x 2 area, similar to Dr. Fire Rosalina's skill but it affects a smaller area. In versus mode, he eliminates objects in a 1 x 1 area at level 1, a 2 x 2 area at level 2 and a 3 x 3 area at level 3 to 5 (the skill meter fills faster at higher levels). This skill prioritizes areas that contain viruses, but if there are no more viruses, the area in which is targeted will be random as long as it contains at least one object.

Other appearances

The Legend of Zelda: Link's Awakening

Zelda Wiki article: Boo

Boos as they appear in the remake of The Legend of Zelda: Link's Awakening

Boos in The Legend of Zelda: Link's Awakening only appearing in a dark room in the games' second dungeon, Bottle Grotto. They actively chase Link regardless of whether he is facing them or not; if Links swings his sword at them, they disappear and reappear at a different location. After Link lights up the room, they become vulnerable and can then be defeated with Magic Powder. In the Nintendo Switch remake of the game, they now use their voice clips from the Super Mario franchise, and a Boo figure can be won from the Trendy Game after clearing the Key Cavern and placed in the Quadruples' house. The text that appears upon acquiring the figure reads, "You got a Boo figure! As spooky ghosts go, this one's pretty cute!"

Minecraft

Boo as it appears in Minecraft

Additionally, in the Super Mario Mash-up in Minecraft, Ghasts are replaced by Boos.

Monopoly Gamer

In Monopoly Gamer, Boo is a playable character, though it is sold separately as a "Power Pack" expansion figure.

Unused appearances

Super Mario Odyssey

Boos were going to appear physically in Super Mario Odyssey, as one is seen in concept art for the game, but they were removed from the game, making this game the first game in the Super Mario series to not contain Boos since Super Mario Land. However, Peach wears a Boo mask on the side of her head when she visits Bowser's Kingdom, a common way to wear masks of yōkai in festivals in Japan.

The Super Mario Bros. Movie

Boos were planned to appear in the film, as they can be seen in early concept artwork for the Dark Lands, but they were removed from the final release. However, their leader, King Boo, makes an appearance during the wedding between Bowser and Peach.