Dormammu — Benedict Cumberbatch
Just like Deadpool sort of faced himself when he battled Juggernaut for a while, Doctor Strange did it too in the movie where he voiced villain Dormammu and did some facial capture work as well. He even claimed it was his idea:
“I went, ‘Look, if this is going to work, rather than being a big ghoulish monster, if it’s some kind of reflection of him — if it’s something that he’s giving that’s coming back at him in a really horrific way, that would be fun! … a lot of the animation is sort of like a mirror reflection, a rippled mirror reflection, of him, of Strange.”