King Boo is a villain in the Mario series. His first real appearance was in Luigi's Mansion for the GameCube. He was in the very top of the attic, and appeared to simply be a super-sized Boo wearing a crown. After defeating him, Mario appears. King Boo re-appears in Super Mario 64 DS, where the selected character must go through a very dangerous maze that often leads back to the beginning. He also still has a grudge against Luigi. Since then, he has appeared as a character (playable or non-playable) in most Mario spin-off games. His most recent appearance was in Mario Super Sluggers. He has chemistry with Petey Piranha, Wiggler, Boo, and King K. Rool.