You tried to kill me, Randy...but you can't kill what's already dead.
~ The Undertaker to Randy Orton during their 2005 feud on WWE SmackDown!
Undead beings are generally either an animated corpse or manifestation of a deceased being's spirit but come in countless more specific varieties and are almost always portrayed as evil in fiction. They are opposed to Revived villains that have been brought back to life and restored to their original form. However, some villains can be both.