These are villains whose fate is truly unknown because the author is not making any more stories or the TV show, movie, or video game is cancelled.

NOTE: This category only applies when the story ended prematurely, not for when it was intentionally inconclusive.

Some villains with unknown fates can also be Complete Monsters as it can leave to unanswered questions as to how the villain(s) would have developed if the story was completed (e.g. Turbo Mecha Sonic). Therefore, even for villains who are still alive and active and have not died/been slain by the time the story ends prematurely, they can still qualify if they meet all the criteria and meet such standards.