The Boohemoth is a giant Boo that appears in New Super Mario Bros. 2 on the Nintendo 3DS. Encountered in the Ghost House in World 2, it can be told apart from regular Boos by its white irises, flat teeth and inflated cheeks. It is the largest Boo to appear in the franchise and is completely invincible, suffering no effects from any of the Mario brothers' power-ups.
The Boohemoth appears in the main corridor of the World 2 Ghost House, suddenly appearing behind the player when they enter. It will then give chase and the player must keep ahead of it at all times until reaching the end of the stage. Because of its great size, the Boohemoth cannot be jumped over or otherwise avoided. While turning to stare at it will stop it temporarily, the Boohemoth will occasionally peek through its hands and inch closer even when being looked at. The player must stay ahead of the Boohemoth and avoid getting cornered, otherwise they will automatically lose a life.