User blog comment:KillRoy231/Top 10 villains that will never die (or stay dead)/@comment-30634893-20171218201529

Ultron and Brainiac  are pretty good examples, given that, every time they are "killed", they just download themselves into a computer or something and rebuild themselves. Doomsday too, considering that he will just regenerate with immunity to what previously killed him.

Of course, most comic book villains and heroes never seem to stay dead, but these three have  legitimate reasons for so.