Tales from the Darkside: Inside the Closet

A student takes a room with an abrupt, somewhat rude anthropology professor. He instructs her never to open the small door in the back of her closet. Hearing strange noises, she eventually opens the door and finds the chamber beyond occupied by a small, hairless-monkey sort of a creature. It kills her and goes after the professor...only to reveal that it is his deformed daughter, which he lovingly dotes on.