The Worldkillers are biological weapons created on Krypton by Kryptonian scientists. Most of them were genetically modified alien species, although at least one Worldkiller was a symbiotic parasite. Realizing those weapons were blood-thirsty, uncontrollable, super-powerful threats to all living beings, the Kryptonian Science Council outlawed them and ordered their destruction. Zor-El's -Supergirl's father- was genuinely regretful about taking part in their creation but he didn't destroy them as he was supposed to.
Five Worldkillers survived the demise of Krypton. They woke up some while after the planetary cataclysm, knowing nothing but their names, their purpose and their origin. Reign was the leader and yearned for knowing how and why they were created, but Krypton was gone and would provide no answers to her questions. They wandered over the galaxy for a long while, during which Worldkiller-1 left the group, until Reign's search led her to Earth. Noticing that world was the only planet in the universe inhabited by Kryptonian survivors, Reign figured Earth might hold answers to her questions and decided to conquer it. However, Supergirl fought them off and drove them out.
Meanwhile, the fifth Worldkiller decided his life's mission was to strengthen alien worlds by culling the weak and helpless individuals of every race. To that end, he possessed the body of the ruler of the Diasporan race and sent his army off to massacre worlds. Supergirl first met the Diasporans when she and the Red Lantern Corps saved planet Grax from them. Worldkiller-1 thought Supergirl -a Red Lantern Kryptonian- was the perfect vessel so he lured her into a trap and tried to bond with her. After a tough battle, Kara hurled him into the Sun, and he got disintegrated.
Equipment: None known.
Transportation: None known.
Weapons: None known.
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- No trivia.