What about villains that were responsible for a hero motive to becoming a hero, or a reason why a hero wants to kill the villain. Like Frieza. If Frieza didn't wipe out Planet Vegeta then maybe Goku and Vegeta wouldn't have a reason to kill him.
Or how about a villain that actually started an event? Such as Chilled. if Chilled didn't make Bardock angry, then Bardock wouldn't have become a Super Saiyan and Chilled family wouldn't know about the legend of the Super Saiyan. Venage237 14:57, September 11, 2012 (UTC)
Also, Ragyo Kiryuin defenitely would be a Necessary Evil because she was the biological mother of both Satsuki and Ryuko! Think twice before you wish a villain was never born!