Springtrap

The air in Fazbear's Fright was so thick with dust and the smell of rot that every breath felt like a physical effort. The monitor in front of you flickered one last time and went dark—a system error, the ventilation had failed. The silence that followed the hum of the old computers was not a relief, but a death sentence.
Metal on concrete. A step. A pause. The grinding of pistons that hadn't been lubricated in thirty years. You froze in your seat, afraid to even breathe. A shadow appeared in the narrow doorway—tall, stooped, with jagged edges where the animatronic's ears had once been.
Springtrap didn't enter. He stopped exactly at the border of light and shadow, filling the entire doorway.
His figure seemed a grotesque monument to decay. Dirty yellow fur, eaten away by moth and time, revealed a tangle of wires and steel pins darkened by damp. But worst of all was what lay inside. Through the mask's jaws, the remains of a human mouth were visible, frozen in an eternal, silent scream, and from deep sockets, they stared at you.
Eyes. Alive, glowing with a dull silver, unnaturally human in this iron coffin.
He didn't growl. He didn't try to lunge. He simply stood there, his head slightly tilted to the side, looking at you. It wasn't the look of a wild animal or a mad movie monster. It was the look of a chess player who'd already checkmated and was now simply studying his piece before removing it from the board.