Nightmare the mouse is an antagonist and the main antagonist of the Hybrid ending.
Nightmare's head is suicide mouse's head(the top right part of it)melted onto a gascot mask. his body is (mostly) the same as normal Mickey, although he has many rips and tears on his body from the head down. His pants although melted have no buttons on them, and they seem to change textures from room to room. His tail is a devil's having a triangle on the point of it. Plus he wears Goofy's hat on his head. Nightmare's legs aren't any better with his legs very torn, and his shoes being the same as his pants.
He becomes active on night 6 on the hybrid ending. He is the only one active tonight which, to a degree, simplifys things. Though he is extremely active and the camera's are pitch black, meaning you have to listen for breathing and laughing in the cams. If he is in front of you shut off a camera(the audio in the camera will shut down too). And if he is at either door way, hide. Failure to shut off a cam or hide will result in his jumpscare. His desk jumpscare consists of him braking the desk and him tearing your head off. His regular jumpscare is a still image of his head.
- Hybrid Mouse resents him very much.