Agamotto

Agamotto is a powerful being in Marvel comics. He was one of the first socerer suppreame for earth. He captured and sealed away in another dimention. He returned in the Eye of Agamotto part 1, and full appearance in Part 2, where he is revealed to be evil and he changed the most of the Avengers into there evil counter parts. It took the will power of Hulk and the mind of Doctor Strange to reseal him back in his dimention.