Nightmare Suicide Mouse was a antagonist in Five Nights at Treasure Island: The End of Disney.
He appears to have sharp "teeth" in his eyes and mouth. He's also missing his right ear, and has human-like eyes.
He'll walk around the building at random and eventually appear at the left office exit. Shining the light at him will not make him go away. To get rid of him, the player must pull up the monitor and shut off a camera. Failing or neglecting to do so will make him attack the player.
He will start on Character Prep 1,then move to Staff Area,then to Meat Freezer,and then the office. the player needs to shock him at this point otherwise a jumpscare will occur.