Dormammu

Dormammu is a demon that exists in the dark dimension. He considers himself as the ruler of humanity. He and his army of Mindless Ones attempted to break through the barrier between Earth and the Dark Dimension. He caught Doctor Strange, but lost in a battle between him and Doctor Strange, A-Bomb and Hulk. He instead hide in Doctor Strange amulet and escaped in to the real world but defeated by the Agents of S.M.A.S.H., the house and Doctor Strange. Dormammu is consider to be one of Dr. Strange's toughest enemies.