Source: total-geeks.com

5. Cyborg Superman

Hey. Can you tell I have a thing for Superman villains with creepy visual designs?

Cyborg Superman was arguably the best thing to come out of the whole Death of Superman thing. And, as someone who's read through the entire death/funeral/reign of the supermen/return thing more than once, there isn't a lot in there worth salvaging. But the cyborg? Oh, yeah, he is.

Hank Henshaw was a run-of-the-mill, one-off villain. In a parody of the Fantastic Four's origin, Hank was one of a crew of astronauts who were irradiated in space and returned with powers that were actually slowly and horribly killing them. But Hank didn't die. He actually gained the ability to force his consciousness into machines. Using this, he slowly but steadily built himself a new body. When Superman seemed to have died, Henshaw turned himself into a cyborg duplicate before turning evil in the least surprising twist of all time.

Henshaw would make a great Superman villain, and would also make a great foe for a Superman/Green Lantern team-up film, since he has history with both characters.