Waylon Jones was born with a rare mutation that made his skin green and scaly, while his body took on grotesque proportions. He was raised by an abusive aunt and constantly experienced bullying due to his appearance. For a time, he worked as a sideshow attraction in a circus under the name Killer Croc, but his misanthropy and bestial nature grew, leading him down a path of crime. As his physical and mental condition deteriorates, Killer Croc becomes a more bestial adversary, drifting further away from humanity.