Bigger Boo

Bigger Boo is the mid-boss of World 2 in Super Mario World 2: Yoshi's Island. He is encountered by Yellow Yoshi at the end of World 2-4, Bigger Boo's Fort, starting out as a normal Big Boo. However, Kamek arrives and uses his magic to increase the size of the Boo. He does not attack Yoshi, instead floating around the room and chasing him when he isn't looking, and he can still be stopped by facing his direction, though he also turns intangible, meaning that he cannot be attacked. The player must toss eggs in a way that they ricochet off the walls and into him while facing away from him, though with each hit Bigger Boo increases in size. After hitting him five times, Bigger Boo's size increases to a point where he explodes, defeating him.

in the Mario Party series
Though not identified as such, Bigger Boo appears in the early titles of the Mario Party sub-series as an obstacle in certain minigames. In both appearances, it is semi-transparent and has a silver aura around its body. It is also able to consume players and trap them within its colossal body. It is also impossible to damage it physically, and the only way to beat it is to reach the end of the minigame without being caught.

Mario Party
Bigger Boo is depicted in Mario Party is the antagonist and most prominent obstacle in the minigame Running of the Bulb, and the players must avoid contact with him at all costs. Throughout the minigame, smaller Boos will attempt to possess the players and make them walk into Bigger Boo. If the player holding the light bulb is consumed by Bigger Boo, the minigame is over and all four players lose. The only way to defeat Bigger Boo is by successfully reaching the end of the stage and plugging the light bulb into the power generator, causing Bigger Boo and all the remaining normal Boos to vanish.

Mario Party 2
Bigger Boo (referred to simply as "Boo" in-game) once again returns for Mario Party 2's rendition of Skateboard Scamper, where it emerges from a painting in a darkly-lit mansion, and the players must race away from it on skateboards without being swallowed whole by the ghostly behemoth. The player that reaches the end first pulls open the curtain, unleashing a ray of sunlight into the room that causes Bigger Boo to vanish.