Nightmare Mangle is the nightmarish version of Mangle and is an antagonist in Five Night at Freddy's 4: Halloween Edition. It is one of the few new Nightmare animatronics alongside Nightmare Balloon Boy and Nightmarionne. It is a nightmarish and more vicious version of Mangle. Nightmare Mangle is responsible for replacing Nightmare Foxy in the Halloween Edition, and thus shares the same behavior.
Overall, it appears to resemble the original Mangle, except far more twisted and tattered. It possesses all of the original parts from Mangle, such as the plastic head, endoskeleton head, and various mechanical parts, but appears far more sinister and twisted, though not as much as Nightmare Balloon Boy. Its head shape looks similar to Nightmare Foxy's, while the second endoskeleton head closely resembles a skull. Nightmare Mangle also has 3 endoskeleton legs.
Nightmare Mangle behaves almost exactly like its counterpart, Nightmare Foxy. Nightmare Mangle is first introduced on Night 2. It will try to enter the Bedroom from either hall. If it succeeds in doing so, it will then enter the Closet. Like Nightmare Foxy, at this point, if the player fails to check the Closet frequently enough, then Nightmare Mangle will come out and jumpscare the player. while Nightmare Mangle is in the closet static noise starts playing, making surviving far harder as it drowns out most audio cues.