Fishing Boo
Fishin' Boos are the spirits of Fishin' Lakitu found in Super Mario World and Super Princess Peach. They carry a fishing rod and ride a Lakitu's Cloud, much like the living variety. However, instead of a 1-Up Mushroom, Fishin' Boos carry a blue flame and follow Mario or Luigi in a way that makes it hard for them to Jump. A Fishin' Boo has the same immunities as a normal Boo and therefore cannot be jumped on.
Fishin' Boos also make an appearance in Super Princess Peach. A calmer variety called Calm Fishin' Boo also appears. Only Rage destroys them. The appear in Shriek Mansion on Vibe Island.
They were also supposed to appear in New Super Mario Bros. Wii since an unknown object was named similar to Fishin' Boo.
An "Fishin' Boo" appears in Mario & Luigi: Bowser's Inside Story in Bowser's level up screen. However, it was actually a Boo with a fishing rod and not an undead Lakitu.