Kaecilius by Camo-Flauge
Kaecilius was a dark sorcerer who opposed the Ancient One, and more recently her apprentice Doctor Strange. He intended to call upon the power of the Dark Dimension to free the Dread Lord Dormammu and make himself and the entire planet immortal so that no one would be able to share the loss he felt by the death of fellow sorceress Adria. However, Strange was able to defeat Kaecilius by making a bargain with Dormammu to leave the planet forever in exchange for taking the wicked sorcerer with him, turning him into an immortal rock-like skeletal being known as the Mindless One and trapping him in the Dark Dimension for all eternity.