|Location(s)||Big Boo's Haunt|
|Received When Killed||Blue Coin|
Boos ingame are small and completely white. They have a red mouth with four sharp teeth, and they have large blue eyes. Looking at most Boo's turns them entirely transparent, revealing a blue coin.
Boos have no attack other than trying to ram into Mario and his friends.
Like in the earlier Mario games, Boo's will turn invisible and intangible if Mario faces them. If Mario turns his back to them, they will fly at him and Mario needs to use the ground pound to defeat them.
If Mario successfully ground pounds the Boo, it will tumble away and instantly be defeated, only leaving behind the aforementioned blue coin.