Editing King Boo

{{FA}}
{{about|the character debuting in ''[[Luigi's Mansion]]''|his ''[[Super Mario Sunshine]]'' counterpart|[[Big Boo (character)]]}}
{{character infobox
|image=[[File:Mario Party Star Rush King Boo.png|250px]]<br>Artwork from ''[[Mario Party: Star Rush]]''
<!--DO NOT CHANGE THIS TO HIS LUIGI'S MANSION ARTWORK. Please see "Template:character infobox" for more information.-->
|species=[[Big Boo]]<br>[[Boo]] (''[[Luigi's Mansion]]'')
|first_appearance=''[[Luigi's Mansion]]'' ([[List of games by date#2001|2001]])
|latest_appearance=''[[Super Mario Party Jamboree]]'' (cameo) (2024)
}}
{{quote|I am not afraid of [[Luigi|you]], fool! I fear only that infernal [[Poltergust 3000]] you carry on your back! Stupid machine! But I am a KING among [[Boo]]s! I swear it... I shall fear no mere house-cleaning device!!|King Boo|Luigi's Mansion}}
'''King Boo''' is a [[List of characters|character]] introduced in ''[[Luigi's Mansion]]''. He is both the main antagonist and arch-nemesis of [[Luigi]] in the [[Luigi's Mansion (series)|''Luigi's Mansion'' series]], which also includes him as the leader of the [[Boo]]s and [[Ghost (Luigi's Mansion series)|ghosts]]. King Boo is allied with [[Bowser]], whom he has assisted on various occasions. He has captured [[Mario]] in every game of the ''Luigi's Mansion'' series, prompting Luigi to rescue him. King Boo's main powers include materializing objects and spitting fire, though King Boo's power is often directly proportional to the number of Boos in his vicinity.
==History==
===''Luigi's Mansion'' series===
====''Luigi's Mansion''====
{{LM portrait infobox
|image=KingBooGold.png
|width=200px
|full_name=Bowser and King Boo, the Dastardly Duo (GameCube){{ref needed}}<br>King of Boos (3DS)
|age=Unknown
|biography=Nothing is known about this mysterious entity. (GameCube){{ref needed}}<br>
The giant Boo adorned with a crown. It's hard at work on other evil plans involving the other Boos. (Nintendo 3DS)
|room=[[Roof (Luigi's Mansion)|Roof]]/[[Secret Altar]]
|hp=500
}}
[[File:KingBoowser.jpg|thumb|upright=1.1|left|Artwork from ''Luigi's Mansion'', showing King Boo escaping from his Bowser suit]]
[[File:LM 3DS Bowser King Boo.png|thumb|left|Screenshot from the 3DS version of ''Luigi's Mansion'', depicting the boss fight against King Boo]]
Prior to the events of ''[[Luigi's Mansion]]'' and its [[Luigi's Mansion (Nintendo 3DS)|remake]], King Boo somehow freed [[Boolossus]], who had been captured by [[Professor E. Gadd]] at some point, then King Boo ordered the release of every other [[Ghost (Luigi's Mansion series)|ghost]] that E. Gadd had captured.<ref>{{cite|quote=Well, then. Now I have to tell you...a horrifying story... The last ghost I caught was No. 22, Boolossus, but there are lots of Boos, and King Boo rallied them all to take revenge upon me! They used my machine to free Boolossus from the painting... then they went and turned all my other portraits back into ghosts, too!|author=Professor E. Gadd|title=''Luigi's Mansion''}}</ref> After releasing all the portrait ghosts, King Boo created a [[Luigi's Mansion (location)|haunted mansion]] near [[Professor E. Gadd's Lab]]. Luigi later receives a scam letter, presumably from King Boo, stating that he had won the mansion, and plans to celebrate over there with Mario.<ref>{{cite|publisher=Nintendo of America|language=en-us|date=2001|title=''Luigi's Mansion'' instruction booklet|page=6}}</ref> However, King Boo imprisons Mario into a portrait,<ref>{{cite|quote=I see! This is King Boo! ...SO! He is the one who has captured your Mario!|author=[[Madame Clairvoya]]|title=''Luigi's Mansion''}}</ref> and places him in the [[Secret Altar]].

During gameplay, King Boo is first seen in the [[Storage Room (Luigi's Mansion)|Storage Room]], where he and the other fifty [[Boo]]s spring out from the floor after Luigi opens it. When King Boo notices the [[Poltergust 3000]] on Luigi's back, he orders the Boos stop their surprise attack and retreat.<ref>{{cite|quote=What's that he's got on his back!? It's E. Gadd's Poltergust 3000! Everybody scram!|author=King Boo|title=''Luigi's Mansion''}}</ref> King Boo is located in the Secret Altar in the mansion's basement for the remainder of the game. Aside from the [[Key#Luigi's Mansion|Secret Altar Key]], reaching King Boo requires Luigi to have caught at least 40 Boos, or else King Boo blows Luigi to the [[Foyer (Luigi's Mansion)|Foyer]]. In the Secret Altar, King Boo stares at Mario in the painting while insulting the brothers' intelligence for having fallen for his scheme.<ref>{{cite|quote=... Seriously, though, who would actually believe that mansions get given away in contests?! Talk about stupid! What do they feed you Mario brothers anyway...gullible soup?|author=King Boo|title=''Luigi's Mansion''}}</ref> King Boo turns around to face Luigi and states his desire to add a Luigi painting to the collection. After this, King Boo flies into the Mario painting, which is changed to depict Bowser instead, and he inhales Luigi into the painting. Luigi is transported into an arena modeled after the [[Roof (Luigi's Mansion)|roof]], and this is where the final boss fight occurs. It is actually just a Bowser suit controlled by King Boo during the battle, both to retreat in and for attacking Luigi. Attacks from the Bowser suit include shooting flames at Luigi (dealing 10 HP of damage), throwing [[Spiked Ball]]s (also dealing 10 HP of damage), or inhaling Luigi and spitting him out, inflicting 15 HP of damage. King Boo emerges from the Bowser suit after Luigi shoots a Spiked Ball at the Bowser suit right before its inhaling attack, blasting off Bowser's head. King Boo has 500 HP, more than any of the other [[portrait ghost]]s, and as Luigi depletes King Boo's health, the Bowser suit's head hovers around the arena, shooting icy blasts, which can freeze Luigi on contact. Seconds later, King Boo returns into the dormant Bowser body and the head reattaches itself. The process repeats throughout the battle, but once King Boo's life falls below 200 HP, the head of the suit reattaches backwards when King Boo returns into the suit, which then runs around aimlessly before properly reorienting his head. When King Boo is vacuumed into the Poltergust 3000, Luigi automatically receives King Boo's [[Crown (King Boo)|Crown]]. Back at the [[Portrificationizer Chamber]], both King Boo and the fake Bowser can be seen in the [[Ghost Portrificationizer]] as it presses them and the other portrait ghosts of area 4 back into paintings, marking an end to Luigi's journey. King Boo and the fake Bowser are both included within the same portrait.
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====''Luigi's Mansion: Dark Moon'' / ''Luigi's Mansion 2 HD''====
[[File:King Boo Artwork - Luigi's Mansion Dark Moon.png|thumb|left|Artwork from ''Luigi's Mansion: Dark Moon'' depicting King Boo's redesigned appearance]]
King Boo reprises his role as both the main antagonist and final boss of ''[[Luigi's Mansion: Dark Moon]]''. He escaped some time after [[Professor E. Gadd]] had sold the portrait of King Boo from [[Luigi's Mansion|the previous game]] at a garage sale (a car boot sale in British English versions).<ref>{{cite|quote=I wonder how he escaped from his portrait in the first place! Hmm, maybe I shouldn't have sold it at the garage sale...|author=Professor E. Gadd|title=''Luigi's Mansion: Dark Moon''}}</ref> King Boo shatters the [[Dark Moon]] into six pieces with a bolt of energy from his crown, turning the [[Ghost (Luigi's Mansion series)|ghosts]] of [[Evershade Valley]] into becoming hostile, mischievous beings that serve King Boo. Towards the climax of Luigi's journey, in which he recovers the Dark Moon shards from each of the mansions, King Boo is revealed to have trapped Mario in a painting again. King Boo later captures Luigi after he recovers the last Dark Moon piece and pulls him back into [[??? (Luigi's Mansion: Dark Moon)|his dimension]]. King Boo makes Luigi realize that he had escaped from the painting and broke the Dark Moon. King Boo intends to use the ghosts as an army to conquer both Evershade Valley and the [[Mushroom Kingdom]] while also planning to put Luigi, E. Gadd, and all their friends into paintings for revenge. King Boo then engages into battle with Luigi, where his attacks include summoning a series of magic lightning bolts with his crown and attempting to slam Luigi with his body. The latter causes [[Spike Ball|spiked ball]]s to fall from above, which will roll around the tilting platform to pose a hazard. King Boo will stop moving when looked at, and when caught underneath a falling ball he will become stunned, leaving him vulnerable to the [[Poltergust 5000]]. Once his HP is depleted and he gets sucked into the Poltergust 5000, he immediately breaks out and sends Luigi into a floating hallway. He then swells to a large size and begins rolling after Luigi, attempting to stall Luigi with various obstacles, such as falling shelves and suits of armor with large polearms. If King Boo does hit Luigi, he will pause for a moment to laugh maliciously. Once Luigi makes it out of the hall, he will land on another tilting platform, where King Boo will repeat his previous patterns at a higher intensity. The battle concludes after the third battle and second hallway chase, leading to King Boo being defeated and sucked into the Poltergust 5000.

King Boo's appearance is derived from ''Luigi's Mansion'', albeit larger and with an additional full set of teeth and sped-up voice from other games in the [[Super Mario (franchise)|''Super Mario'' franchise]]. Some of King Boo's new features include a purple tongue and mouth and glowing purple eyes.

====''Luigi's Mansion Arcade''====
King Boo is the final boss in ''[[Luigi's Mansion Arcade]]''. He leads his ghosts in an uprising to get revenge on Luigi and E. Gadd. King Boo assaults Luigi on the [[Terrace (Luigi's Mansion: Dark Moon)|terrace]] of the [[Treacherous Mansion]], after Luigi has sucked in all of his minions with the [[Poltergust 5000]]. Protected by a magical barrier, he can only be attacked once he lets his guard down. King Boo throws bombs at the player, moves very quickly and clones himself multiple times over the course of the fight. However, only the original has the power-enhancing gem on his crown. Just like in ''Luigi's Mansion: Dark Moon'', he escapes the Poltergust 5000 two times before being defeated for good.

====''Luigi's Mansion 3''====
[[File:LM3 E3 screen 04.png|thumb|Screenshot from ''Luigi's Mansion 3'', showing King Boo chase Luigi down a hallway]]
King Boo is the main antagonist and final boss in ''[[Luigi's Mansion 3]]''. King Boo utilizes his design from ''Luigi's Mansion: Dark Moon'', but with more detail on his crown and a more expressive scowl. King Boo had been released from Professor E. Gadd's custody by [[Hellen Gravely]], hoping to win his affection. Seeking revenge on Luigi for his previous defeats, King Boo traps E. Gadd, Mario, [[Princess Peach]] and the three [[Toad (species)|Toads]] in portraits before going after Luigi, who narrowly avoids it by going down a laundry chute. King Boo later entrusts Hellen Gravely with Mario's portrait. It is implied that King Boo planned for Luigi to win both due to Gravely's failures by that time and so he could capture both alongside Peach by using the latter as bait, also recapturing the Toads and Professor E. Gadd just after Mario was freed. King Boo fails to capture Luigi again atop the hotel because the [[Polterpup]] shoved Luigi out of the way of King Boo's portrait. Following this is a battle against King Boo, who can take damage from Luigi throwing a [[bomb]] from a spiked ball into his mouth, then from having his tongue pulled from Luigi and [[Gooigi]] together and being slammed repeatedly. After this, King Boo will generate a clone that attacks alongside him. The clones have only two teeth, like King Boo from ''Luigi's Mansion''. After this is done twice, King Boo will enlarge the painting, and Luigi will then have four minutes to attack King Boo one last time. However, a [[Gold Bone]] can reset the timer. The battle ends with King Boo being recaptured by Luigi and placed in a containment jar alongside Gravely, much to his frustration. As the purple gem in his crown was taken by Luigi after the final battle, it is missing from his crown.<ref>{{cite|author=ProsafiaGaming|date=October 30, 2019|url=youtu.be/GYyMEi0iTZw?t=643|timestamp=10:43|title=Luigi's Mansion 3 - All Endings & Ranks + Credits|publisher=YouTube|accessdate=November 20, 2019}}</ref> The [[Game Over]] sequence shows King Boo gleefully looking at Luigi and the others trapped in their own portraits.

===''Super Mario-kun''===
[[File:KingBoo SuperMarioKun.jpg|thumb|A depiction of King Boo in ''Super Mario-kun'']]
King Boo appears in a short chapter on ''Luigi's Mansion'' of volume 26 of ''[[Super Mario-kun]]''. Luigi reveals King Boo by knocking off the Bowser illusion's head, though King Boo is immediately sucked into the Poltergust 3000, unlike the games.

===''Mario Kart'' series===
====''Mario Kart: Double Dash!!''====
[[File:Petey Piranha and King Boo - Mario Kart Double Dash.png|left|thumb|175px|Artwork from ''Mario Kart: Double Dash!!'', showing King Boo and Petey Piranha as partnered racers]]
King Boo is an unlockable character in ''[[Mario Kart: Double Dash!!]]''. It is the first playable appearance of King Boo. He is partnered with [[Petey Piranha]] by default. Both characters are unlocked simultaneously by placing first in the [[Star Cup]] in Mirror Mode. King Boo is billed a heavyweight, due to his large size. He and Petey Piranha can uniquely use nearly every other character's [[Special Item (Mario Kart series)|Special Item]], barring the [[Green Fireball]] or the [[Birdo's Egg]]. King Boo's personal kart is the [[Boo Pipes]], which is a gray version of Petey's [[Piranha Pipes]] kart, but with an image of a Boo on the pipe stood on by the back driver. Additionally, it notably has a low speed stat and high acceleration stat, in contrast with the other heavyweight karts in the game. King Boo appears to slightly shrink when he becomes the driver. On the second "Thanks for Playing!" screen, King Boo appears in the background chasing [[Wario]] and [[Waluigi]].

In the {{file link|MarioKartDoubleDashDebugMenuBossTeresa.png|debug menu}} found in the demos and debug build of the game, King Boo is referred to as "Boss Teresa," the name used for the [[Big Boo (character)|Big Boo]] boss from ''[[Super Mario 64]]'' and ''[[Super Mario Sunshine]]'' outside localized releases, instead of his usual name "King Teresa".

====''Mario Kart DS''====
King Boo is a boss in ''[[Mario Kart DS]]''. He is the encountered at the end of Level 4 in Missions Mode, where he is battled by [[Princess Peach|Peach]] on the [[Lava Arena]]. King Boo appears every few seconds, stealing at least ten coins collected by Peach around the course and making all uncollected coins disappear before teleporting to another area. Peach can drive through King Boo to retrieve the coins and cause the others to reappear. King Boo is defeated once all fifty coins are collected by Peach.

A variation of the King Boo and Bowser portrait from ''Luigi's Mansion'' appears in the [[DS Luigi's Mansion|titular race course]], except King Boo is not depicted in it.

====''Mario Kart Arcade GP 2''====
King Boo makes a cameo in ''[[Mario Kart Arcade GP 2]]''. A large picture of him appears near the end of [[Yoshi Park 2]], inhaling many ghosts and the racers and returning racers to the start of the course.

====''Mario Kart Wii''====
[[File:MKW SNES Ghost Valley 2 Screenshot 2.png|thumb|left|Screenshot from ''Mario Kart Wii'']]
King Boo is an unlockable playable character in ''[[Mario Kart Wii]]''. He is billed a large-sized driver. King Boo is unlocked by either completing the [[Star Cup]] in 50cc or playing 750 races. King Boo features a good handling bonus and a small off-road bonus. King Boo is one of the few characters whose his standing animation on the character select screen has been changed from ''Mario Kart: Double Dash!!'', no longer hanging his tongue out of his mouth prior to being selected. King Boo is the character used by the Staff Ghost on the {{classic-link|SNES|Ghost Valley 2}} course. He is seen during the end credits driving the [[Jetsetter]] on said course.
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====''Mario Kart 8 Deluxe''====
[[File:MK8D King Boo Battle Mode Screenshot.png|thumb|Screenshot from ''Mario Kart 8 Deluxe'', showing King Boo wear a crown in [[Battle Mode]]]]
King Boo is a playable character in ''[[Mario Kart 8 Deluxe]]''. He does not appear in [[Mario Kart 8|the original]]. King Boo is among the lightest of the five heavyweight groups, sharing his statistics with [[Rosalina]], [[Link]], and [[Pauline]]. King Boo has the lowest top speed and weight of all the heavyweights, all while sharing similar acceleration as other heavy groups. Both King Boo's handling and mini-turbo boost is amongst the best of the heavyweights (shared with the [[Metal Mario|metal]] [[Pink Gold Peach|characters]] and Petey Piranha). His traction stat is noticeably strong, and it is the highest compared to others in his weight class. King Boo has the third best base traction stat out of every racer. King Boo's horn sound uses the same sound effect as the ''[[Super Mario Sunshine]]'' [[Big Boo (character)|boss of the same name]] makes when hit by a [[pepper]]. King Boo is the 150cc Staff Ghost for {{classic-link|GBA|Boo Lake}} and the 200cc Staff Ghost for three courses: [[Twisted Mansion]], {{classic-link|GBA|Snow Land}}, and {{classic-link|3DS|Rosalina's Ice World}}. Although without a rival in Grand Prix in the base game, King Boo was uniquely given a rival in [[Petey Piranha]] since the fifth wave of the ''[[Mario Kart 8 Deluxe – Booster Course Pass|Booster Course Pass]]'', and vice-versa.

====''Mario Kart Arcade GP DX''====
King Boo is a playable character in ''[[Mario Kart Arcade GP DX]]''. He is a super handling type character, sharing his stats with [[Baby Mario]] and [[Baby Peach]]. He was originally only playable during a limited-time event campaign held between October 18, 2017, and January 10, 2018, but not in international releases. King Boo could become available even after the event if Bana Passport users collected three in-game stamps, though an update on October 10, 2018 made King Boo available for users who did not participate in the aforementioned event.

====''Mario Kart Tour''====
[[File:MKT King Boo Luigi's Mansion.jpg|thumb|left|170px|King Boo (Luigi's Mansion) in ''Mario Kart Tour'']]
King Boo is a playable character in ''[[Mario Kart Tour]]''. He was introduced in the 2019 [[Halloween Tour (2019)|Halloween Tour]]. King Boo is classified as a Super driver, and his [[Special skill (Mario Kart Tour)|special skill]] is the [[Lucky Seven]]. King Boo has two variants were introduced, including '''King Boo (Luigi's Mansion)''', also introduced in the 2019 Halloween Tour, uses his design from ''Luigi's Mansion 3''. This variant is listed as a High-End character and has the [[Bob-omb Cannon]] special skill. '''King Boo (Gold)''' was introduced for the 2020 [[Halloween Tour (2020)|Halloween Tour]], sporting a golden body and blue-jeweled silver crown. Also listed as a High-End driver, he uses the [[Coin Box]] as his special skill and, like other metallic characters, a distorting filter is applied to his voice. Unlike most characters, King Boo's head icon is recycled from ''Mario Kart 8 Deluxe'', rather than having a new one that uses his in-game model. Similarly, the head icons for his ''Luigi's Mansion'' and gold counterparts also use their in-game artwork.

In pre-release materials, including the [[List of Mario Kart Tour pre-release and unused content|beta test]], King Boo was classified as a Super Rare (High-End) driver and his special skill was the [[Double Bob-ombs]], sharing his change in classification between the beta test and final game with Rosalina.
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===''Super Mario'' series===
====''Super Mario 64 DS''====
[[File:King Boo SM64DS boss fight.png|thumb|Screenshot from ''Super Mario 64 DS'' of the boss fight against King Boo]]
King Boo,<ref>{{cite|title=''Nintendo Power'' Volume 188|date=February 2005|page=79|publisher=Nintendo of America|language=en-us|author=Tsuboike, Yoshio, et al.|quote=(Luigi’s being held captive by King Boo, so you’ll have to rescue him first.)}}</ref> though erroneously named Big Boo in {{wp|Western world|Western}} releases,<ref>{{cite|quote=Eee hee hee! I am Big Boo, the spookiest of all the spirits! I locked up the [[Luigi|wimpy green moustache man]]. And I'll do the same to [[Mario|you]]! Eee hee hee! Since I'm a ghost, I can turn invisible in the mirror's reflection. You'll have to attack me from behind to defeat me. But you'll die of fright before that ever happens! And then you'll be one of us!|author=King Boo (Big Boo)|title=''Super Mario 64 DS''}}</ref> is a boss in ''[[Super Mario 64 DS]]''. King Boo and Big Boo use the same model, with a modifier denoting the presence of the crown. King Boo is located in a room at the end of [[Big Boo Battle]]. The audibility of King Boo's cackling voice is a guide for Mario to navigate his way through several rooms to the end. King Boo is only ever visible from the mirror in the arena, and can be attacked from being [[stomp]]ed when approached closely enough. After being defeated, King Boo drops the [[Luigi Key]] he had been guarding, allowing the player to unlock Luigi's door in the [[Peach's Room|princess's room]]. King Boo can be fought against optionally by other player characters (barring [[Yoshi]]), including [[Luigi]] and [[Wario]]. King Boo's dialogue when encountering Luigi shows him to be confused but deciding to attack Luigi nonetheless. In their initial encounter, King Boo is shown to be alarmed by Wario's appearance.

====''New Super Luigi U'' / ''New Super Mario Bros. U Deluxe''====
King Boo makes a cameo appearance in ''[[New Super Luigi U]]'' and ''[[New Super Mario Bros. U Deluxe]]''. His art from ''Luigi's Mansion: Dark Moon'' can be seen in the form of a sign hanging from the side of the building in the secret exit of [[Vanishing Ghost House]].

====''Super Mario Bros. Wonder''====
[[File:SMBWKingBoo.png|thumb|left|Screenshot from ''Super Mario Bros. Wonder'']]
King Boo is an enemy in ''[[Super Mario Bros. Wonder]]''. This is the first game including him as a regular enemy.<ref name=CM>{{cite|language=ja|author=Nintendo 公式チャンネル|date=September 28, 2023|url=youtu.be/SiLFeqd99cw|title=スーパーマリオブラザーズ ワンダー CM ワンダー篇|publisher=YouTube|accessdate=September 28, 2023}}</ref> King Boo chases the player characters while singing with an operatic baritone voice. King Boo covers his face when looked at, though continues singing, albeit with a voice distortion filter. When the player characters collect the [[Wonder Seed]], King Boo's crown will fall off as he shrinks into a regular Boo.<ref>{{cite|author=YTSunny|date=October 19, 2023|url=youtu.be/KWRFFbE5OXc|title=Super Mario Bros Wonder - All Songs / Music Levels|language=en|publisher=YouTube|accessdate=November 4, 2023}}</ref> King Boo appears in [[Light-Switch Mansion]] after activating the [[Wonder Effect]] "A Night at Boo's Opera." and in [[The Final Battle! Bowser's Rage Stage]] upon reaching the Jack-o-Lantern pumpkins. Once players enter the zero-gravity section, King Boo again loses his crown, shrinks into a regular Boo, and floats away off-screen surrounded with music notes.<ref>{{cite|author=Mixeli|date=October 19, 2023|url=youtu.be/jRiP86jxIME|title=Super Mario Bros. Wonder - Final Boss Bowser Battle and Ending (HQ)|publisher=YouTube|accessdate=November 4, 2023|language=en}}</ref>

====''Super Mario Run''====
A statue of King Boo in his ''Luigi's Mansion: Dark Moon'' design was made available in ''[[Super Mario Run]]''{{'}}s Kingdom Builder during the ''[[Luigi's Mansion 2 HD]]'' event that coincided with the latter game's release. It is unlocked by completing six "Luigi's Ghost Hunt" missions.
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===''Mario Baseball'' series===
====''Mario Superstar Baseball''====
King Boo is a default playable character in ''[[Mario Superstar Baseball]]''. He is a member of [[Wario]]'s baseball team, the [[Wario Muscles|Wario Greats]]. Being billed a Power character, King Boo can hit long outfield drives and even home runs. King Boo has good batting, although curved like Boo's, and he has average pitching and fielding and a slow running speed. King Boo's ability is [[Super Jump (Mario Baseball series)|Super Jump]], allowing him to catch high balls in the outfield. King Boo shares good chemistry with [[Boo]] and [[Petey Piranha]] but bad chemistry with [[Luigi]] and [[Baby Luigi]]. King Boo uses the same baseball bat as Boo, but with a crown on top.

====''Mario Super Sluggers''====
[[File:MSS King Boo Batting Screenshot.png|thumb|left|Screenshot from ''Mario Super Sluggers'', showing King Boo batting at [[Yoshi Park]] during the night]]
King Boo is a playable character in ''[[Mario Super Sluggers]]''. His stats are similar as before, although his pitching is improved and matches his batting power. King Boo's ability is Teleport, allowing him to teleport safely onto the base during close plays if performed correctly. King Boo shares good chemistry with Petey Piranha, Boo, [[Wiggler]], and [[King K. Rool]] whilst having bad chemistry with [[Mario]], Luigi, [[Yoshi]], [[Baby Mario]], Baby Luigi, [[Baby Peach]], and [[Baby Daisy]]. The baseball bat used by King Boo was redesigned to have a crown emblem above the Boo emblem instead of an actual crown on top. In this game only, the colors of the jewels on King Boo's crown are reversed. In Challenge Mode, King Boo is a member of Wario's team, the Wario Muscles, and appears right after defeating [[Bowser Jr.]] at the [[Wario City]] stadium, stating that he turned invisible and was watching the whole game. However, he is uninterested in joining the player's team unless the team has Boos with them, more specifically the [[Mini Boo]] item.
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===''Super Princess Peach''===
[[File:Shriek Mansion 3-6.png|thumb|Screenshot from ''Super Princess Peach'', showing the battle against King Boo]]
King Boo is a boss in ''[[Super Princess Peach]]''. He is encountered in [[Shriek Mansion 3-6]]. While going after [[Princess Peach]], King Boo attacks by firing blue homing [[fireball]]s. King Boo can be damaged from direct light, which is created by having his own flames light the candles spread throughout the room. After a few attacks, King Boo uses his [[Gloom]] vibe to cry and therefore extinguish the candle flames. King Boo is eventually defeated from enough hits, and Peach rescues the [[Toad (species)|Toad]] he had been guarding.

===''Mario Party'' series===
====''Mario Party 8''====
King Boo is a non-playable character in ''[[Mario Party 8]]''. He is the proprietor of the board [[King Boo's Haunted Hideaway]]. He hides in one out of three altars and gives a [[Star (Mario Party series)|Star]] to whoever can find him in exchange for ten Coins. King Boo returns the player to the starting point from a [[Warp Pipe]] through "summoning the bizarre" after they purchase the Star while also altering the layout of the board, which also ejects any other players from the board. If the player does not have enough coins, or declines his Star, King Boo causes a pitfall to appear beneath them, returning the player to the starting point without any Star, and he does not shuffle the board. There are purchasable King Boo sounds from the [[Fun Bazaar]], along with a figurine titled "King Boo's Revenge". When the player presses {{button|wii|A}} on the figurine during the Figurine Parade, King Boo floats upward while glowing. During the board event, Pickpocket Pinball, if the player does not manage to steal anything, the hosting [[Little Mouser|mouse]] gives off a sound similar to King Boo's.

====''Mario Party 9''====
[[File:MP9 King Boo's Puzzle Attack 1.png|thumb|left|Screenshot from ''Mario Party 9'', showing King Boo in his minigame, King Boo's Puzzle Attack]]
King Boo is a boss in ''[[Mario Party 9]]''. He is encountered at [[Boo's Horror Castle]], being fought in the minigame, [[King Boo's Puzzle Attack]]. King Boo takes damage from competitors lining power-up icons in lines of three or more. Upon reaching half damage, King Boo starts throwing Boos onto the field that can stun the player's cursors. In the minigame [[Bowser's Block Battle]], King Boo can materialize above the stage when Bowser throws the die with all the stage bosses' faces on it and if it lands with King Boo's face on top. King Boo summons five Boos that move in a counterclockwise direction while moving outwards. When the Boos reach the boundaries of the stage, King Boo summons five Boos that move clockwise instead. After that, King Boo disappears from the arena. King Boo also has his own constellation, the "Ghost Major," which is placed in farthest left portion of the sky, near [[King Bob-omb]]'s constellation and right next to Boo's constellation after buying it for fifty Minigame Points. The [[Mario Party 9#Museum|Museum]]'s Sound Test has two voice sounds named "King Boo's Entrance," one of which is of King Boo and the other being Boo.
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====''Mario Party 10''====
[[File:King Boo's Tricky Tiles MP10.png|thumb|Screenshot from ''Mario Party 10'', showing King Boo in his minigame, King Boo's Tricky Tiles]]
King Boo is a boss in ''[[Mario Party 10]]''. He is fought in the minigame [[King Boo's Tricky Tiles]]. King Boo is damaged from player characters jumping on light switches. After losing half of his health, King Boo becomes angered and begins a new attack where he swaps Boos with platforms and blocks the camera, preventing players from memorizing the platforms more clearly. In amiibo Party mode, King Boo can be found on the [[Luigi Board]].

====''Mario Party: Star Rush''====
King Boo is a boss in ''[[Mario Party: Star Rush]]''. He is fought in the minigame [[King Boo's Light Smite]]. King Boo is damaged from player characters shining a light from their [[Light Box]]es at him. After losing half of his health, King Boo increases the difficulty by having the rotating platforms move faster and causing more Peepas to appear.

====''Mario Party Superstars''====
King Boo is a non-playable character in ''[[Mario Party Superstars]]''. He appears on [[Horror Land]], replacing the [[Big Boo (character)|Big Boo]] found on the original board.<ref>{{cite|author=Nintendo|date=September 23, 2021|url=www.youtube.com/watch?v=dG9fAtmYdlM|title=Nintendo Direct - 9.23.2021|publisher=YouTube|accessdate=September 23, 2021}}</ref> King Boo summons Boo lackeys to steal either Coins or Stars from all opponents who have any, with the latter option costing 150 coins. King Boo is encountered at nighttime only and through a path that requires a [[Skeleton Key]], like with Big Boo from the original version.

====''Super Mario Party Jamboree''====
[[File:SMPJ King Boo Reaction.png|thumb|80px]]
Although King Boo himself does not physically appear in ''[[Super Mario Party Jamboree]]'', he makes a cameo as a selectable reaction.<ref>Mario Party Legacy (September 9, 2024). [https://www.youtube.com/watch?v=Nnv5j5d8_Ho 10 Minutes of Super Mario Party Jamboree - Gameplay Preview]. ''YouTube''. Retrieved September 9, 2024.</ref>

===''Mario & Sonic'' series===
====''Mario & Sonic at the Olympic Winter Games''====
[[File:King_Boo_-_Winter_Games.jpg|thumb|left|Screenshot from the Wii version of ''Mario & Sonic at the Olympic Winter Games'', showing King Boo and Mario competing in Alpine Skiing Downhill]]
King Boo is a non-playable character in the [[Mario & Sonic at the Olympic Winter Games (Wii)|Wii version]] and the [[Mario & Sonic at the Olympic Winter Games (Nintendo DS)|Nintendo DS version]] of ''Mario & Sonic at the Olympic Winter Games''. Both games feature King Boo as a rival, but in differing way. In console versions, King Boo is the first opponent in both Individual and Group Festival modes, challenging the player to the [[Alpine Skiing Downhill]] event, while Individual Festival includes him again as the sixth opponent, this time challenging the player to [[Giant Slalom]]. In the Adventure Tours mode of the handheld version, King Boo is the mid-boss of [[Polastraits]], where he specifically chooses Luigi to race him in Giant Slalom due to his fearful nature. In both versions, King Boo travels downhill smoothly, not having any skis, to which [[Cream (character)|Cream]] or [[Toad]] considers to be unfair in the console version. King Boo can be traveled through in the handheld version only.

====''Mario & Sonic at the London 2012 Olympic Games''====
[[File:M&S 2012 The Ghostly Tower.png|thumb|Screenshot from the 3DS version of ''Mario & Sonic at the London 2012 Olympic Games'', showing King Boo in [[The Ghostly Tower]] episode]]
King Boo is a non-playable character in the [[Mario & Sonic at the London 2012 Olympic Games (Wii)|Wii version]] and [[Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)|Nintendo 3DS version]] of ''Mario & Sonic at the London 2012 Olympic Games''. He is a rival in both versions, but his role differs entirely, and the handheld version also features King Boo as a [[List of badges in Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)|badge]] that can be obtained from the badge machine. In the console version, King Boo is encountered in London Party mode, challenging the player to the [[Dream Sprint]] event and offering stickers as a reward for beating him. In the handheld version, King Boo has a brief role in Story Mode, guarding the [[Phantasmal Fog]] at the [[Tower of London]], and teams up with a Boo to challenge [[Sonic]] and [[Tails]] in [[Badminton (Doubles)]], though King Boo and Boo both lose and flee. King Boo is last seen in Story Mode during the opening ceremony for the games.
{{br|left}}
====''Mario & Sonic at the Sochi 2014 Olympic Winter Games''====
King Boo is a non-playable character in ''[[Mario & Sonic at the Sochi 2014 Olympic Winter Games]]''. He is a rival in [[Legends Showdown]] mode, during Area 4, where he challenges the player to [[Short Track Speed Skating 1000m]].

===''Mario Golf: World Tour''===
King Boo is a non-playable character in ''[[Mario Golf: World Tour]]''. He floats in the background alongside other [[Boo]]s on Hole 4 of [[Bowser's Castle (golf course)|Bowser's Castle]]. King Boo's name is sometimes displayed on the tournament scoreboard.

===''Super Smash Bros.'' series===
There are a few items of King Boo in the [[Super Smash Bros. (series)|''Super Smash Bros.'' series]]. In ''[[Super Smash Bros. for Nintendo 3DS]]'', there is a [[Trophy (Super Smash Bros. series)|trophy]] of King Boo. In ''[[Super Smash Bros. Ultimate]]'', King appears in his ''Luigi's Mansion: Dark Moon'' design as an Advanced-class Neutral-type {{iw|smashwiki|primary spirit}}, which is enhanced from the Boo primary [[Spirit (Super Smash Bros. Ultimate)|spirit]] after it has reached level 99. When equipped, the spirit grants the fighter slower fall speed after jumping and has 3 support slots. King Boo is listed as the 49th spirit, though he was listed as the 121st spirit alongside the rest of the spirits from the ''Luigi's Mansion'' series in version 1.0.0.<ref>{{cite|author=BeardBear|date=December 6, 2018|url=youtu.be/CiK68gO5XQM?t=336|timestamp=05:36|language=en|title=Super Smash Bros. Ultimate - All 1297 Spirits|publisher=YouTube|accessdate=May 26, 2024}}</ref>

===''Puzzle & Dragons: Super Mario Bros. Edition''===
[[File:PDSMBE-KingBoo-TeamImage.png|thumb|Graphic from ''Puzzle & Dragons: Super Mario Bros. Edition'']]
King Boo is a boss and enemy in ''[[Puzzle & Dragons: Super Mario Bros. Edition]]'', mostly appearing at the Ghost House courses. His main attribute is Dark, while his sub-attribute is Light. As an ally, King Boo's skill can heal 1000 HP, and change all Heart Orbs into Dark Orbs. His Awoken Skill raises the amount of time that the player has to move Orbs around.

As an enemy, King Boo is capable of decreasing the player's maximum time to move Orbs around. Also, King Boo is treated as a generic enemy, so he can still appear as an enemy, regardless of whether or not the player has King Boo in their party. Big Boo can be transformed into a King Boo with six [[Boo Mushroom]]s as a Transformation Item, making it possible to create multiple King Boos on the player's team.

When King Boo attacks, a bunch of [[Boo]]s attack with him.

King Boo's best stats are his ATK and RCV, while his HP is at an average level.

===''Mario & Luigi: Paper Jam''===
{{quote|Look at this little scrap. Friend of yours, is he? Well, if you like your friend, you better stop attacking me! Now, don't go thinking it's OK to attack my little minion either. Who knows what could happen if he dropped your little friend there... You got that?|King Boo|Mario & Luigi: Paper Jam}}
[[File:M&L Paper Jam King Boo.png|thumb|left|250px|King Boo, attempting to fool Mario and Luigi by disguising himself as Paper Mario, in ''Mario & Luigi: Paper Jam'']]
King Boo is a boss in ''[[Mario & Luigi: Paper Jam]]''. King Boo has a papercraft version of himself piloted by [[Morton]] and [[Lemmy]], which is fought in [[Bowser's Castle]]. The Mario Bros. use Papercraft Yoshi to fight it.

The real King Boo is encountered and fought in [[Gloomy Woods]] after the trio separate, leading to him kidnapping Mario and [[Paper Mario (character)|Paper Mario]]; leaving Luigi alone to find them, similarly to the ''Luigi's Mansion'' series. After finding [[Mario]], he and Luigi begin to look for Paper Mario. They eventually find King Boo instead, disguised as Paper Mario. When they group together, King Boo reverts back to normal and laughs at the Bros. for a second, before re-transforming; Mario and Luigi then turn around, and are unaware of King Boo's presence. When they turn around again, King Boo reveals himself again, but is caught by the duo. In an attempt to fool them, he immediately reverts back to Paper Mario, and tries to convince the Bros. that he is the real Paper Mario, but fails. King Boo then loses control of his transformation powers, as he quickly transforms into Paper Peach and then Paper Bowser, before finally gaining control and giving up; reverting back to his true form, causing the battle to commence.

King Boo attacks by spitting blue fireballs at either Mario or Luigi before inhaling them; making them need to avoid the fireballs twice, and splitting into five copies before floating slowly towards the trio, turning invisible as he gets near; which the trio must counter using their hammers around 2 seconds after a copy turns invisible. During the battle, King Boo calls a [[Paper Boo]] holding the real Paper Mario onto the battlefield; threatening to harm Paper Mario if the bros attack either himself or the Paper Boo. In order to save Paper Mario, Mario and Luigi must defeat the minion holding onto Paper Mario, causing it to drop him. If King Boo is attacked while the Paper Boo is on the battlefield, he deals damage to Paper Mario. After a few turns, another Paper Boo can grab Paper Mario again, taking him out of the battle (which gets rid of Paper Mario's copies) temporarily. Finally, King Boo also has a chase attack where he grows bigger before attempting to shoot a giant blue fireball at the trio; which Mario and Luigi have to counter by throwing Paper Mario's boomerang form into King Boo's mouth while it is open. Once defeated, Paper Mario is reunited with the duo and the group continues to [[Mount Brrr]]. 

King Boo's crown leaves him unaffected by the brothers' [[Jump]] attack, though he can be hit by [[Hammer]] attacks, unlike Paper Boos, and certain [[Bros. Attack]]s, such as the [[Rocket Blast]] and [[Mega Thwonk]]'s jumping attacks (only in the [[Arcade (Mario & Luigi: Paper Jam)|arcade]]). Attacking King Boo from above results in the Bro. taking 1 damage in the manner of jumping on a spiked enemy. The [[Dropchopper]], however, can circumvent this as it can be aimed towards King Boo's forehead instead of his crown and can then damage him.

The splitting attack used by King Boo is a reference to (if not a direct copy of) the [[Dark Star]]'s splitting attack in ''[[Mario & Luigi: Bowser's Inside Story]]'', except King Boo takes damage if countered unlike the Dark Star's version due to it being invincible. As well, if the Mario Bros. continue to attack King Boo without freeing Paper Mario, his slapping Paper Mario may be an allusion to [[Lady Bow]] and her slap attacks<ref>{{cite|author=Gaming Reinvented|date=January 8, 2016|url=www.youtube.com/watch?v=74SYLTwZ2Aw|title=Mario & Luigi Paper Jam; King Boo Kills Paper Mario!|publisher=YouTube|accessdate=February 7, 2024}}</ref>. Also, King Boo's voice clips from ''[[Mario Kart Wii]]'' are reused.
{{br}}

===''Mario + Rabbids Kingdom Battle''===
King Boo makes a cameo appearance in ''[[Mario + Rabbids Kingdom Battle]]''. He is seen in [[Spooky Trails]], where an image of King Boo appears on the ground in the area where the gramophone is found.

===''Mario Tennis Aces''===
King Boo is a boss in ''[[Mario Tennis Aces]]'', as of version 2.0.0. His voice clips are identical to a Boo's. King Boo is part of the Boo Hunt Co-op Challenge. King Boo hovers around the court while Frenzy Time is active, and can be hit by several tennis balls to earn the players more [[coin]]s. King Boo disappears once either his health bar or the Frenzy bar is depleted.

===''Dr. Mario World''===
[[File:DMW-Dr. King Boo Solo Art.png|thumb|100px|Dr. King Boo in ''Dr. Mario World'']]
King Boo is an assistant in ''[[Dr. Mario World]]'', as of the November 14, 2019 update.<ref>{{cite|author=DrMarioWorld_EN|date=November 14, 2019|url=x.com/Drmarioworld_EN/status/1195137397639536641|title=Blue: "Tiers 6 and 7 were added to versus mode! Apparently you can add a new assistant, King Boo, from the battle boxes for tier 7. You need 2,600 battle points to reach tier 7, but I know you can do it!" #DrMarioWorld|publisher=X|accessdate=September 28, 2020}}</ref> He is a battle box-exclusive assistant, only obtainable from battle boxes for tier 7 or above in versus mode. In versus mode, he has a chance of sending 2 extra rows of viruses to the opponent if the attack lands. In stage mode, he grants a chance of 5 extra capsules being added when 5 capsules are remaining, which will have a chance to activate again if the condition is met again but didn't activate earlier. However, it won't activate for the rest of the stage if this effect has successfully activated. 

'''Dr. King Boo''', available September 28th, 2020, is an alias of King Boo exclusive to ''Dr. Mario World''. Like [[Dry Bowser|Dr. Dry Bowser]], he cannot be obtained in staffing and must be obtained through either in-app purchases or unlocking him through rewards such as in [[World 20]]'s Special Stage or through certain referrals. His skill is to eliminate an amount of viruses even those that would normally take multiple hits to clear such as [[floatie virus]]es. In stage mode, the amount is 5 viruses (4 prior to version 2.2.0), while in versus mode, the amount differs based on level, where it is 4 at level 1 with three extra viruses per level, up to 16 at the maximum level of level 5. In stage mode, if there are no more viruses while this skill is activated, it will eliminate one random object that can be eliminated instead, excluding capsules. 
{{br}}

===''The Super Mario Bros. Movie''===
[[File:King Boo TSMBM Screenshot.png|thumb|120px|King Boo in ''The Super Mario Bros. Movie]]''
King Boo has a minor appearance in ''[[The Super Mario Bros. Movie]]'' at Bowser and Peach's wedding with his ''Super Mario'' design. He is seen sitting a few rows behind [[King Bob-omb]]. He does not have any role in the climax nor does he speak. He disappears once Peach, Mario, and [[Donkey Kong]] crash the wedding. Compared to his usual design, his face is smaller and is more expressive, taking up less space on his overall body and somewhat resembling that of the ''[[Super Mario Sunshine]]'' [[Big Boo (character)|King Boo]]. He is also the only Boo that appears in the movie.
{{br}}

==General information==
===Physical appearance===
{{multiple image
|align=right
|direction=horizontal
|footer=King Boo's recurring design (left) and his design for the ''Luigi's Mansion'' series (right)
|image1=King Boo Artwork MSS.png
|width1=175
|image2=LM3 King Boo artwork.png
|width2=166
}}
King Boo has appeared with two distinct designs, one used in most of his appearances and one used for the [[Luigi's Mansion (series)|''Luigi's Mansion'' series]].

King Boo's common design was first used in ''[[Mario Kart: Double Dash!!]]'', where he appears as a large Boo with a golden, five-pointed crown. With this design, the crown has a blue jewel on the front and four red jewels around the sides in every game except ''Mario Super Sluggers'', where the colors are reversed. Like other Boos, King Boo is generally shown with an open, wide grin; however, when looked at, he closes his mouth and bashfully hides his face with his hands. In certain games like ''[[Mario Party 9]]'', King Boo's emotions are denoted by an aura surrounding him: when happy, he glows with a blue aura, and when angry, he glows with a red aura. Sometimes he also has steam coming out of him to display his anger. In ''[[Dr. Mario World]]'', he has a doctor's mirror on his crown and he carries a medicine box by strap. His gold variant in ''[[Mario Kart Tour]]'' is based on this design, and has an entirely golden body similar to a [[Gold Boo]], though his teeth and tongue are golden as well. His crown is silver and all five jewels are blue.

King Boo has a more unique and sinister look in the ''Luigi's Mansion'' series. In his original appearance in ''[[Luigi's Mansion]]'', King Boo has dark red eyes, a blue tongue, two vampire-like fangs, a greenish complexion, and a ruby in a gold, round-edged crown. He is also roughly the same size as other Boos. Starting from ''[[Luigi's Mansion: Dark Moon]]'', King Boo retains his original appearance but with some modifications: he now has a full row of four teeth, a white body, and a larger size matching those of King Boo's modern ''Super Mario'' design. Additionally, he has purple eyes, a dark indigo mouth and tongue, and a purple jewel atop his crown, which has additional pointed edges. He also has a larger shadow surrounding his eyes. In ''[[Luigi's Mansion 3]]'', King Boo is shown to be more expressive, often scowling at his allies and enemies and appearing visibly disappointed when captured in the game's credits. His speech icon also uses a green shading reminiscent of his initial appearance, while his portraits show him with a purple crown. In ''Mario Kart Tour'', King Boo's ''Luigi's Mansion'' variant uses this design, although his tongue is more purple than indigo.

===Personality===
[[File:LM3 2D Artwork 1.png|thumb|King Boo shows a particular disdain for Luigi in the ''Luigi's Mansion'' series.]]
King Boo is a villain who enjoys scaring and tricking his enemies by creating illusions and then overpowering and trapping them. King Boo likes to taunt Luigi, such as in ''Luigi's Mansion 3'', where he says "It's-a me, King Boo!", mocking Luigi's and Mario's Italian accent. In ''Luigi's Mansion: Dark Moon'', King Boo pretends to confuse between Luigi and Baby Luigi. In ''[[Mario & Sonic at the Olympic Winter Games (Nintendo DS)|Mario & Sonic at the Olympic Winter Games]]'', he insists on racing against Luigi, knowing how afraid he is of ghosts. King Boo also holds grudges, referring to his prior defeat in ''Luigi's Mansion'' sarcastically as "good times" and he has stated that he is "sick to double death" of Luigi. In frustration, he recites the noise of the [[Poltergust 3000]], which he refers as a "disgusting machine", capturing him.

King Boo admires paintings and other decorations, such as making lengthy comments on how good Mario is as a painting; E. Gadd also comments that King Boo has decorated [[Treacherous Mansion]] to be scarier. He also desires to trap Luigi and E. Gadd through similar means.

King Boo boasts frequently about himself, always proclaiming his success in escaping and claiming to fear nothing except the Poltergust 3000, although in ''[[Super Mario 64 DS]]'' he admits that Wario's face scares him. Despite his power, he still covers his face in fear when looked at, much like a normal Boo. King Boo has a distinct cackle, which is quite lower in pitch than other Boos. King Boo's arrogance is displayed in ''Mario & Sonic at the Olympic Winter Games'', where he claims to be unbeatable at Alpine Skiing.

===Powers and abilities===
In ''[[Luigi's Mansion]]'', King Boo's power increases when he is in the presence of other Boos. For example, King Boo can blow Luigi to the Foyer when enough Boos are in the mansion. King Boo can also materialize things, including pulling a mansion out of the ghost dimension, creating replicas of some of Mario's enemies, other Boos, dimensions to battle in, bubbles, and blue fire (which he spits out of his mouth). King Boo can regenerate from his crown in ''[[Super Princess Peach]]''

In ''[[Luigi's Mansion: Dark Moon]]'', King Boo can open [[paranormal portal]]s to the ghost dimension, create traps such as sand patches, electrify terrain to shock Luigi, grow to large sizes, and teach Boos how to create [[Spirit Ball]]s. His new crown can also shoot an ectoplasmic laser that can shatter the [[Dark Moon]] or trap [[Toad (species)|Toads]] within paintings. King Boo can create illusions, hence his title "The Master of Illusions." In this game, similar to ''Luigi's Mansion'', his power is stronger when there are other Boos in the vicinity. 

[[File:LM3 King Boo Final Battle.png|thumb|left|King Boo can create clones and shoot fireballs from his crown in the final battle of ''Luigi's Mansion 3''.]]
In ''Luigi's Mansion 3'', King Boo summons magical paintings to trap people and, to a certain extent, objects inside. He can enlarge portraits in order to capture people, as an extension of his paranormal portals. He does not need the presence of other Boos to grow stronger in this game.

King Boo has a high power stat in many of his spin-off appearances. This is most noticeable in the [[Mario Baseball (series)|''Mario Baseball'' series]], where he is able to hit home runs easily. His great strength is also shown in ''Luigi's Mansion: Dark Moon'', as he summons and makes spike balls fall down simply by slamming the platform.  

In ''[[Mario & Luigi: Paper Jam]]'', King Boo shapeshifts to trick Mario and Luigi by posing as Paper Mario, and he later briefly transforms into Paper Peach and Paper Bowser. He can also spit blue fireballs.

===Relationships===
====Enemies====
{{quote|You think I'll let you get away with that!? You're going down this time, Green 'Stache!|King Boo|Luigi's Mansion Arcade}}
King Boo and Luigi are arch-nemeses in the ''Luigi's Mansion'' series. King Boo's motivation for trying to imprison Mario and Luigi is for revenge that both brothers have posed trouble against him in the past. King Boo additionally dislikes Professor E. Gadd for his ghost-capturing hobby, involving capturing his Boos. King Boo additionally states that the only thing that scares him is E. Gadd's invention, the Poltergust 3000.  In ''[[Mario Superstar Baseball]]'', King Boo has negative chemistry with Luigi and [[Baby Luigi]]; in ''[[Mario Super Sluggers]]'', he has bad chemistry with Mario, [[Princess Peach]], [[Princess Daisy]], [[Baby Mario]], [[Baby Peach]], [[Baby Daisy]], and [[Yoshi]]. King Boo also traps Toads in ''Luigi's Mansion: Dark Moon'' and captures Princess Peach in ''Luigi's Mansion 3''.

Generally speaking, King Boo cares nothing for ghosts that are not Boos, considering them expendable to advance his grand schemes such as in ''Luigi's Mansion: Dark Moon'' where he caused friendly ghosts to turn hostile so he can try to take over Mushroom Kingdom. Even Hellen Gravely, who has great admiration for King Boo, is seen by him as nothing more than a tool for his plans, and he deems her useless as she fails to capture Luigi.

====Friends====
[[File:MP9 Bowser Block Battle 15.png|thumb|King Boo assists Bowser by summoning Boos in ''Mario Party 9''.]]
King Boo has been shown to work with Bowser on numerous occasions, including ''Super Mario 64 DS'', ''Mario Party 9'', and ''Super Princess Peach''. He also used a Bowser decoy and the two share a portrait after King Boo's defeat in ''Luigi's Mansion''. Despite this, the two share neutral chemistry in ''Mario Superstar Baseball'' and ''Mario Super Sluggers'', with King Boo appearing on [[Wario]]'s team rather than Bowser's. King Boo has also been paired up with [[Petey Piranha]] in ''Mario Kart: Double Dash!!'', with the two sharing chemistry in the ''Mario Baseball'' games and sharing several statistics in ''Mario Kart 8 Deluxe'' as well as the same CPU vehicle parts, with both acting as rivals for each other upon Petey's inclusion through the ''[[Mario Kart 8 Deluxe - Booster Course Pass|Booster Course Pass]]''. King Boo also has good chemistry with [[Wiggler]] and King K. Rool in ''Mario Super Sluggers''. ''[[Luigi's Mansion 3]]'' shows [[Hellen Gravely]] admiring King Boo, with her releasing him to impress and aid him in his plot for revenge against Luigi. King Boo pays little consideration toward Hellen Gravely and is more interested in capturing Luigi and E. Gadd, making Hellen Gravely's admiration one-sided.

King Boo relies on his Boo minions, or "friends,"<ref>{{cite|quote=I must say...I despise the way you SHWEEERRPP-SHLOOOOP-WHOOORPP-SHLEEEOOORG-vacuumed up all my friends!|author=King Boo|title=''Luigi's Mansion''}}</ref> to cooperate with try to capture Luigi and his friends. In ''[[Mario & Luigi: Paper Jam]]'', he threatens to hurt [[Paper Mario (character)|Paper Mario]] if the Mario Brothers hurt his [[Paper Boo]] minion. He has good [[chemistry]] with the playable Boo in the [[Mario Baseball (series)|''Mario Baseball'' series]]. In ''[[Mario Super Sluggers]]'', King Boo says that he finds little Boos cute. However, in the later ''Luigi's Mansion'' titles, he can be just as cruel to them as he is to his other ghost minions, showing no concern for them being sucked up by Luigi and even actively putting them in harm's way, as well as indirectly calling them useless in ''Luigi's Mansion 3''.

==Quotes==
{{main|List of King Boo quotes}}
*"''Aahh, I could just stare at my Mario painting for hours! It's true what they say about fine art...it takes utterly refined sensibilities to truly appreciate it! The way you plead for help, Mario... I find it so...satisfying. Perhaps that is merely because I remember how much trouble you've caused me in the past. ... Seriously, though, who would actually believe that mansions get given away in contests?! Talk about stupid! What do they feed you Mario brothers anyway...gullible soup? Your brother came all this way just to get turned into a painting... It's just terrific. However... This Mario painting looks lonely... I must have a Luigi painting as well! Then my gallery will truly be complete! Bleah HA HA! I am not afraid of you, fool! I fear only that infernal Poltergust 3000 you carry on your back! Stupid machine! But I am a KING among Boos! I swear it... I shall fear no mere house-cleaning device!! I must say...I despise the way you SHWEEERRPP-SHLOOOOP-WHOOORPP-SHLEEEOOORG-vacuumed up all my friends! Don't imagine that I'll flee... I'll fight you like a true Boo! Now join your brother... ...inside the painting!''" - ''[[Luigi's Mansion]]''
*"''Bah! You don't have enough coins! King Boo says boo to you! And good-bye!!!''" - ''[[Mario Party 8]]''
*"''Say WHAT? You want ME to help YOOOOOU?''" - ''[[Mario Super Sluggers]]''
*"''Heh heh heh! I saw that Alpine Downhill event of yours yesterday! Looks like you need to take a lesson in speed from ME! And that lesson starts today! I challenge you to an Alpine Downhill match! Hee hee hee!''" - ''[[Mario & Sonic at the Olympic Winter Games (Wii)|Mario & Sonic at the Olympic Winter Games]]'' (Wii)
*"''...Hmm? One-two-three-four-five-six-sev-- WAIT! There should be seven! Who's missing!? [...] Luigi! What are you doing over there?! UGH! That's it! I'm sick to double death of you! You want to fight me? FINE! Let's go, Luigi! This is the end for you, once and for all! HERE I COME!''" - ''[[Luigi's Mansion 3]]''

==Voice samples==
{{media table
|file1=King Boo's laugh 2004.oga
|title1=''[[Super Mario 64 DS]]''
|description1=King Boo's laughter
}}

==Profiles and statistics==
{{main|List of King Boo profiles and statistics}}

==List of appearances==
{|class="wikitable sortable" width=100%
|-
!width=40%|Title
!width=20%|Description
!width=20%|Release date
!width=20%|System/format
|-
|''[[Luigi's Mansion]]''
|Main antagonist, final boss
|2001
|[[Nintendo GameCube]]
|-
|''[[Mario Kart: Double Dash!!]]''
|Unlockable playable character
|2003
|Nintendo GameCube
|-
|''[[Super Mario 64 DS]]''
|Boss
|2004
|[[Nintendo DS]]
|-
|''[[Mario Superstar Baseball]]''
|Playable character
|2005
|Nintendo GameCube
|-
|''[[Super Princess Peach]]''
|Boss
|2005
|Nintendo DS
|- 
|''[[Mario Kart DS]]''
|Boss
|2005
|Nintendo DS
|-
|''[[Mario Party 8]]''
|Non-playable character
|2007
|[[Wii]]
|-
|''[[Mario Kart Arcade GP 2]]''
|Cameo
|2007
|Arcade
|-
|''[[Mario Kart Wii]]''
|Unlockable playable character
|2008
|Wii
|-
|''[[Mario Super Sluggers]]'' 
|Playable character
|2008
|Wii
|-
|''[[Mario & Sonic at the Olympic Winter Games (Nintendo DS)|Mario & Sonic at the Olympic Winter Games]]'' 
|Rival
|2009
|Nintendo DS
|-
|''[[Mario & Sonic at the Olympic Winter Games (Wii)|Mario & Sonic at the Olympic Winter Games]]'' 
|Rival
|2009
|Wii
|-
|''[[Mario & Sonic at the London 2012 Olympic Games (Wii)|Mario & Sonic at the London 2012 Olympic Games]]''
|Rival
|2011
|Wii
|-
|''[[Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)|Mario & Sonic at the London 2012 Olympic Games]]''
|Rival
|2012
|[[Nintendo 3DS]]
|-
|''[[Mario Party 9]]''
|Boss
|2012
|Wii
|-
|''[[Luigi's Mansion: Dark Moon]]''
|Main antagonist, final boss
|2013
|Nintendo 3DS
|-
|''[[New Super Luigi U]]''
|Cameo
|2013
|[[Wii U]]
|-
|''[[Mario & Sonic at the Sochi 2014 Olympic Winter Games]]''
|Rival
|2013
|Wii U
|-
|''[[Mario Golf: World Tour]]''
|Non-playable character/cameo
|2014
|Nintendo 3DS
|-
|''[[Super Smash Bros. for Nintendo 3DS]]''
|Trophy
|2014
|Nintendo 3DS
|-
|''[[Mario Party 10]]''
|Boss
|2015
|Wii U
|-
|''[[Puzzle & Dragons: Super Mario Bros. Edition]]''
|Boss
|2015
|Nintendo 3DS
|-
|''[[Mario & Luigi: Paper Jam]]''
|Boss
|2015
|Nintendo 3DS
|-
|''[[Luigi's Mansion Arcade]]''
|Main antagonist, final boss
|2015
|Arcade
|-
|''[[Mario Party: Star Rush]]''
|Boss
|2016
|Nintendo 3DS
|-
|''[[Mario Kart 8 Deluxe]]''
|Playable character
|2017
|[[Nintendo Switch]]
|-
|''[[Mario Kart Arcade GP DX]]''
|Playable character <small>(during a limited-time event)</small><br>Unlockable playable character <small>(for permanent use, through a limited-time event)</small>
|2017
|Arcade
|-
|''[[Mario + Rabbids Kingdom Battle]]''
|Cameo
|2017
|Nintendo Switch
|-
|''[[Mario Tennis Aces]]'' (version 2.0.0)
|Boss
|2018
|Nintendo Switch
|-
|''[[Luigi's Mansion (Nintendo 3DS)|Luigi's Mansion]]''
|Main antagonist, final boss
|2018
|Nintendo 3DS
|-
|''[[Super Smash Bros. Ultimate]]''
|Spirit
|2018
|Nintendo Switch
|-
|''[[New Super Mario Bros. U Deluxe]]''
|Cameo
|2019
|Nintendo Switch
|-
|''[[Dr. Mario World]]''
|Assistant (update)
|2019
|iOS / Android
|-
|''[[Mario Kart Tour]]''
|Unlockable playable character (update)
|2019
|iOS / Android
|-
|''[[Tetris 99]]''
|Cameo in TETRIS x Luigi's Mansion 3 Event
|2019
|Nintendo Switch
|-
|''[[Luigi's Mansion 3]]''
|Main antagonist, final boss
|2019
|Nintendo Switch
|-
|''[[Mario Party Superstars]]''
|Non-playable character
|2021
|Nintendo Switch
|-
|''[[Mario Kart Live: Home Circuit]]'' (version 2.0.0)
|Non-playable character
|2021
|Nintendo Switch
|-
|''[[Super Mario Bros. Wonder]]''
|Enemy
|2023
|Nintendo Switch
|-
|''[[Luigi's Mansion 2 HD]]''
|Main antagonist, final boss
|2024
|Nintendo Switch
|-
|''[[Super Mario Run]]'' (version 3.2.0)
|Cameo
|2024
|iOS, Android
|-
|''[[Super Mario Party Jamboree]]''
|Cameo
|2024
|Nintendo Switch
|}

==Gallery==
{{main-gallery|King Boo}}
<gallery>
LuigisMansionKingBooModel.png|''[[Luigi's Mansion]]''
King Boo MKDD Model.png|''[[Mario Kart: Double Dash!!]]''
King Boo ArcadeGP2.png|''[[Mario Kart Arcade GP 2]]''
SPP-King Boo Sprite.png|''[[Super Princess Peach]]''
MP9 King Boo Bust.png|''[[Mario Party 9]]''
MKT Artwork KingBooLuigisMansion.png|''[[Mario Kart Tour]]''
</gallery>

==Names in other languages==
<!--To edit this table, access the "List of King Boo names in other languages" page and go to the "King Boo" section.-->
{{main|List of King Boo names in other languages}}
{{:List of King Boo names in other languages|transcludesection=King Boo}}

==Trivia==
*When King Boo says, "''I will not give up my favorite decoration. I like Mario just where he is,''" he references a quote from {{wp|Jabba the Hutt}} in ''{{wp|Return of the Jedi|Star Wars Episode VI: Return of the Jedi}}''.<ref>{{cite|quote=I will not give up my favorite decoration. I like {{wp|Han Solo|Captain Solo}} where he is.|author=Jabba the Hutt|title=''Star Wars Episode VI: Return of the Jedi''|publisher=Lucasfilms|date=1983|language=en}}</ref>
*King Boo's laugh originating from ''Luigi's Mansion'' is actually a pitched-up version of a stock laughing sound effect.<ref>{{cite|url=soundeffects.fandom.com/wiki/Sound_Ideas,_CARTOON,_LAUGHTER_-_LOW,_THROATY_LAUGH,_HUMAN_01|title=Sound Ideas, CARTOON, LAUGHTER - LOW, THROATY LAUGH, HUMAN 01|publisher=Soundeffects Wiki|accessdate=October 10, 2022}}.</ref> A pitched-down version of the same effect was previously used for [[Bleak]].

==References==
<references/>

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{{Boos}}
{{LM}}
{{MGTT}}
{{MKDD}}
{{SM64}}
{{MSB}}
{{SPP}}
{{MKDS}}
{{MP8}}
{{MKAGP2}}
{{MKW}}
{{Mario Super Sluggers}}
{{M&SATOWG}}
{{M&SATLOG}}
{{MP9}}
{{LMDM}}
{{M&SATSOWG}}
{{MP10}}
{{M&LPJ}}
{{MPSR}}
{{MK8}}
{{MKAGPDX}}
{{MTA}}
{{DMW}}
{{MKT}}
{{LM3}}
{{MPS}}
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{{SMBW}}
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[[Category:Boos]]
[[Category:Shapeshifters]]
[[Category:Portrait ghosts]]
[[Category:Kings|Boo]]
[[Category:Final bosses]]
[[Category:Playable characters]]
[[Category:Dr. Mario World]]
[[Category:LEGO Super Mario characters]]
[[Category:Mario & Luigi: Paper Jam bosses]]
[[Category:Mario & Luigi: Paper Jam characters]]
[[Category:Mario & Sonic at the London 2012 Olympic Games characters]]
[[Category:Mario & Sonic at the Olympic Winter Games characters]]
[[Category:Mario & Sonic at the Sochi 2014 Olympic Winter Games characters]]
[[Category:Mario Golf: World Tour characters]]
[[Category:Mario Kart 8 Deluxe characters]]
[[Category:Mario Kart DS bosses]]
[[Category:Mario Kart Tour characters]]
[[Category:Mario Kart Wii characters]]
[[Category:Mario Kart: Double Dash!! characters]]
[[Category:Mario Party 8 characters]]
[[Category:Mario Party 9 bosses]]
[[Category:Mario Party 10 bosses]]
[[Category:Mario Party: Star Rush bosses]]
[[Category:Mario Party Superstars characters]]
[[Category:Mario Superstar Baseball characters]]
[[Category:Mario Super Sluggers playable characters]]
[[Category:Super Mario Bros. Wonder enemies]]
[[Category:Super Mario-kun characters]]
[[Category:Super Mario 64 bosses]]
[[Category:Super Princess Peach bosses]]
[[Category:Super Smash Bros. for Nintendo 3DS trophies]]
[[Category:Super Smash Bros. Ultimate spirits]]
[[Category:The Super Mario Bros. Movie characters]]
[[de:König Buu Huu]]
[[it:Re Boo]]