Going to point this out but from the lack of visible face and the shape of the actual armor, I think that's more Onslaught, Charles Xavier's evil side that was given physical form in a story arc years ago.
Actually, that would still be Magneto. Age of Apocalypse arc. Notice the white braids hanging down from the more exaggerated helmet. Onslaught had no hair, and had a more extremely muscular frame.
