Lord Voldemort
Towards the end of the story, Harry finds out that one of the teachers at Hogwarts named Professor Quirrell was trying to steal a magical stone called the Philosopher's Stone. Quirrell takes off his turban and reveals that Voldemort's soul is living on the back of his head and that he is trying to get the Stone to revive Voldemort. Quirrell/Voldemort tries to attack Harry but due to the protective spell that his parent's sacrifice gave him, Harry cannot be killed and Quirrell dies while Voldemort's spirit escapes.