10 Comic Book Villains Who Killed Their Greatest Rival
10. Lex Luthor Kills Superman - Superman #149
In a comic that precluded the hero's famous defeat at the hands of Doomsday, Superman #149 sees Luthor accomplish a rare feat, by actually managing to take down the Man of Steel.
After spending what is suggested to be years of time gaining Superman's trust, Lex convinces the spaceman that his life is under threat, and that the only way he can be safe is if the hero helps him build a space station that nobody else can access. Ever the kind soul, Kent agrees, and inadvertently builds his own death trap - as Luthor would trap the Kryptonian in one of the ship's rooms, and expose him to kryptonite until he passed away.
This isn't the only time Lex would be able to pull the wool over Kent's eyes - at one point in his comic career even curing cancer just to get close to the Man of Steel - it's the most successful of Luthor's various machinations, which is also exactly why it's not considered canon.