Nightmare (Five Nights at Freddy's)

Nightmare is a secret antagonist, and a boss in Five Nights at Freddy's 4. His current role in the story is unknown.

Appearance
He is clearly based on Nightmare FredBear, being some sort of demonic version of the already demonic Fredbear. Unlike Fredbear, his skin is translucent, exposing all of his animatronic parts. Upon closer examination, a black mass resides in Nightmare's head, theorized to be the child's frontal lobe.

He is black with a yellow hat and bow tie, the yellow hat having a black trim on it. He only has one button on his chest.

Five Nights at Freddy's 4
Just like Fredbear on Night 6, on Night 7 and Night 8, he takes the same role, appearing at 4 AM, and replacing all animatronics, taking up their duties. He must be handled the same way, but Nightmare is extra aggressive than Fredbear. Upon being attacked by him, he will appear in a screen similar to Golden Freddy instead of a complete animation. His existence is unexplained, and his purpose is unknown. He is acknowledged in the gallery as a separate entity from Nightmare Fredbear, meaning that he must have some sort of significance.

Trivia

 * He is similar to Shadow Freddy in several ways.
 * His current role in the story is unknown.
 * Nightmare is the only one animatronic who doesn't have standing in Extras Menu.
 * Upon close inspection, Nightmare has transparent parts in is body, this could imply that he is a ghost.
 * An opinion gives that his black appearance makes him a spirit.
 * He could be possibly the true main antagonist of the fourth game.