Big Boo's Creeps are anomalous enemies that share their model with Boos. They are commonly described to have green eyes and a green mouth. Big Boo's Creeps are generally described as enemies that, upon spotting the player, will chase the player until they either die or leave the level. They can often phase through walls. Creeps have been noted to be invincible, or only being able to be killed with the Metal Cap if it is available.
Big Boo's Creeps are usually said to appear in Big Boo's Haunt and Big Boo's Forest, though have been reported in other courses. They are said to sometimes be grouped together, and are often said to start appearing after a Big Boo is defeated.
Big Boo's Creeps have been speculated to be Enemy Discoloring, though have more differences from a Boo than regular discolored enemies.