|Location(s)||Big Boo's Haunt|
|Received When Killed||Power Star|
Big Boo is a large, white ghost. It is about thrice as tall as Mario. Big Boo has a red mouth with four sharp teeth, and they have large blue eyes. Looking at it turns it entirely transparent, just like its smaller counterparts, but sans the Blue Coin seen in them.
Big Boo has no attack other than trying to ram into Mario and his friends.
Like in the earlier Mario games, Big Boo will turn invisible and intangible if Mario faces it. If Mario turns his back to it, it will fly at him and Mario needs to use the ground pound to defeat it.
Unlike the regular Boos, Mario needs successfully ground pound Big Boo thrice to defeat it. Each groud pound, that connects, will make Big Boo tumble away for a moment, but unless it is the third hit, Big Boo will regain its balance and attempt to fly towards Mario's location again.
Once Big Boo has been ground pounded the third and final time, it will tumble away and be defeated, leaving behind a Power Star.