Waylon Jones was born with a rare genetic condition that gave him a reptilian appearance with scales, fangs, and claws. He is also superstrong and durable, has enhanced senses and speed, and he can regenerate. Waylon was a sideshow wrestler who turned to a life of crime when he started becoming more animalistic.

Gerry Conway, Don Newton, and Gene Colan created Killer Croc, first with a cameo in Detective Comics #523 (February 1983) then his first full appearance was in Detective Comics #524 (March 1983). Waylon was born with reptilian traits and his mother died while giving birth to him. He was raised by an abusive alcoholic aunt who called him names like “lizard boy” and he later retaliated by killing her.

Killer Croc went on to be a criminal and murderer who was regularly stopped by Batman and Robin/Jason Todd. During the Pre-Crisis period, Killer Croc was originally the person who killed Jason Todd’s parents, but it was later retconned to have Two-Face be the killer.

Killer Croc escaped from custody and sought refuge in an old sewer system where he joined a community of unhoused people. Batman found him down there when he came to warn the sewer dwellers that new water tunnels would flood their home. As the water began to fill the area, Killer Croc held up the walls so that his friends could be freed and he nearly died in the process.

The water forced Croc through a storm drain and he spent months alone, living in the dark. He hallucinated and relived some of the torment he had suffered from his aunt and bullies. Killer Croc killed a vagrant that crossed his path, then went on a rampage that ended at a mall. Batman and Robin were in the middle of fighting Croc when Bane showed up to challenge Croc. Bane broke Killer Croc’s arms, he was captured, and he was sent to Arkham Asylum.

Killer Croc’s life has often been marked by torment and frequent stays in Arkham. He broke out during Knightfall, but his desire for revenge against Bane put him back in the asylum. In Hush, he was given a virus that made him devolve even faster and then Mad Hatter implanted him with a device to make him loyal to Black Mask. Batman freed Croc from the mind control, and when Croc tried to take revenge on Mad Hatter, Batman stopped him.

Later he met a woman named Sybil Silverlock in Arkham. They bonded and Sybil asked him to look after her daughter, Olive, when he got out of the asylum while she was still incarcerated. He traveled to Gotham Academy to keep Olive safe and when Batman found out, he promised to help her too. Killer Croc has also been a member of the Suicide Squad, and though he has been forced to be in Task Force X, he has looked out for his teammates.