Thanos

Thanos was the ruler of The Abyss for thousands of years. He gained his power after obtaining the Infinity Stones and using them to become the sole ruler. However, he was sealed away in The Abyss by the Legendary Dark Knight Donald Mustard. He was later killed by Spitfire in an act of vengeance for killing Tim Sweeney, and to prevent him from entering the human world in Earthbound 15: Guns and Void Creatures Chapter 3.