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Most of these villains who joined the Justice League only did so for a minimal time before returning to their evil ways. Even in the short time these villains were members, they were instrumental in helping save the day from even worse threats. This list will also include characters who started as villains before becoming anti-heroes, because for many of them their time as members of the Justice League was instrumental in their transition to morally gray heroism.
10) Clock King

A C-list villain of Batman and Green Arrow, Billy Tockman, aka Clock King, is a supervillain who plans out his crimes down to the last second. Clock King and several other low-ranking villains formed a new Injustice League. When the Injustice League accidentally thwarted a terrorist attack, they tried to rebrand themselves as heroes. This team of C-List villains was then asked to join Justice League International and was accepted. However, they were made into a new branch, Justice League Antarctica, and sent to the frozen continent to get them out of the real League’s hair. Clock King and the rest of the team were then quickly defeated by genetically altered killer penguins. The Justice League of Antarctica quickly disbanded afterwards, ending Clock Kingโs brief flirtation with heroism.
9) Lobo

The notorious intergalactic alien bounty hunter Lobo is willing to fight and kill anyone if he is in the mood. His role as both a villain and an anti-hero has made him an enemy and ally of the Justice League. Lobo became an official member when Batman recruited him. Batman saved Lobo from the villain Maxwell Lordโs mind control powers. Grateful for the rescue, Lobo joined Batmanโs new Justice League of America team as a favor. Lobo was still a destructive force of nature, but he surprisingly got along with his teammates, especially Atom. Of course, no team can keep the Main Man constrained for long, and Lobo went back to his chaotic bounty hunting lifestyle once he felt that his debt to Batman had been paid.
8) Killer Frost

The third villain to take on the Killer Frost identity, Caitlin Snow, suffered a lab accident that gave her cryokinetic abilities and a need to absorb the life force of others to live. After her arrest by Firestorm and brief time as a member of the Suicide Squad, Killer Frost was paroled and got a chance at redemption. Batman recruited Killer Frost to be a member of his new Justice League of America team, and the villain gladly took the opportunity to make up for her life of crime. She also joined Jon Kentโs version of the team and later the Justice League Unlimited. Although she can sometimes be manipulated back into villainy temporarily, Killer Frost is determined to leave her criminal life behind her for good.
7) Major Disaster

Paul Booker, aka Major Disaster, was a Green Lantern villain with the ability to cause chaos and natural disasters. Major Disaster began as a petty crook and member of the Injustice Gang but tried to redeem himself by joining the Justice League. Unfortunately, he and several other villains became members of Justice League Antarctica instead. However, after the team disbanded, Major Disaster got another chance to be a real hero as a member of the secret task force, Justice League Elite. But though he helped save the world multiple times, Major Disaster sadly fell back into his old criminal ways to support his daughter financially.
6) Harley Quinn

Harleen Quinzel, aka Harley Quinn, with her chaotic and violent personality, at first seems like an odd choice to join the Justice League. Starting as Jokerโs girlfriend/henchwoman, Harley eventually ditched him when she finally realized how toxic he was to her. Since then, sheโs been everything from an independent villain to an anti-hero seeking redemption. And, when the Justice League disappears and is presumed dead, sheโs recruited into Jon Kentโs new Justice League. With the return of the original Justice League and the formation of the vast roster of Justice League Unlimited, Harley was among the numerous new members enlisted, showing just how far sheโs moved on from her origin as Jokerโs lackey.













