Deathlock: The Demolisher was certainly an undead, but of an unusual kind... He was a future General, killed in battle, and revived via cybernetics. He had his own comic, for a while (Marvel/Kirby, I believe?) In his dark-future world, there were many cannibals, and in one scene, he is "talking" to the computer tied into his brain, asking it why they're always following him. The computer replies that they're following the smell of rotting meat...
Deathlock ("A Man locked in death!") somehow got brought back to the present, at some point, and all organic matter removed. After a brief stint as a robotic villian, he was destroyed. As far as I know, nothing ever told what happened to his "organic parts", so perhaps the good General is still around, minus his precious "'puter" and cybernetic components.