In Stranger Things, Henry Creel, also known as Subject 001, is the true villain, revealed in Season 4 as the powerful psychic who becomes Vecna, the mastermind behind the Upside Down and its monsters, orchestrating events from that dimension after being banished by Eleven. He was a troubled boy with powers, later experimented on, who committed mass murders before Eleven sent him to the Upside Down, where he transformed into the monstrous Vecna, seeking revenge on humanity. 