11. The Joker Killed Lex LuthorWell, sort of. Alexander Luthor Jr. hailed from Earth-Three and was a great hero before transforming into one of the multiverse's most despicable villains. After arriving on the DC Universe's main Earth, he put in place an insane plan to try and take control of the world, but was ultimately stopped and fled to Gotham City. Cowering in an alley cursing his failings, this version of Lex Luthor was confronted by the regular versions of Lex and The Joker. It was then that things took a much darker and horrific turn. The latter mutilated Alex's face with an acid flower and proceeded to electrocute him with a joy buzzer as revenge for not inviting him to join his Secret Society of Super Villains. As a smirking Lex (who was furious after Alex impersonated him), The Joker finished off this alternate Earth doppelgänger by blowing his head off point blank with a shotgun. You'd think it would have been strange for Lex to stand back and watch The Joker butcher his alternate Earth counterpart, but he didn't seem at all fazed. Of course, the regular Lex and Joker have always got on reasonably well, especially after forming the Injustice League together.