Boohemoth

Boohemoth is a type of Big Boo that is introduced in New Super Mario Bros. 2. It is one of the largest Boos in the Mario series. Unlike the other members of the Boo species, the Boohemoth has normal human-like incisors instead of fangs, visible cheeks and chin, and it has two eyeholes with a white iris and black pupils. Boohemoth has a very low-pitched laugh compared to its fellow Boos. Its name is a combination of "boo" and "behemoth" (a large, fabled beast in fantasy culture).

New Super Mario Bros. 2
In New Super Mario Bros. 2, Boohemoth appears only in two different Ghost Houses: and. In certain areas of a Ghost House, the Boohemoth appears out of nowhere and starts following Mario or Luigi. It controls the movement of the camera. Just like normal Boos, if Mario or Luigi turns to face it, it closes its eyes with its hands and remains still along with the camera. However, unlike Boos, if Mario or Luigi stare at the Boohemoth for a while when far away from it, it will peek through its hands and slowly sneak up to them.

Due to its huge size, Mario and Luigi can't go through the Boohemoth, and getting crushed between it and an obstacle will kill them. Also, the Boohemoth cannot be defeated by any of Mario's power-ups (even as Gold Mario, Invincible Mario or White Racoon Mario, making it an invincible enemy. The only thing Mario and Luigi can do if the Boohemoth chases them is run away to the exit.

Mario Kart 8
In Mario Kart 8, a Boohemoth can be seen as a statue on top of the entrance of Twisted Mansion.