When I was looking at the list of people I thought half those people arent really THAT evil, especially Magneto, Dr. Doom is somewhat evil but he is more of a power hungary tyrant. Galactus does the things he does to survive. Thanos is pretty damn evil, Beyonder I dont know to much about, Red Skull is a Nazi ( I dont care what your views are but thats evil ). Ironman is NOT evil, plain and simple. Pheonix is the opposite of Galactus, so its just part of her nature.
I say Green Goblin, Red Skull, Thanos, and Apocolypse are the most eveil of the bunch. The hard part for me is ranking these four.