Most of Batman's rogues gallery is comprised of mentally deranged killers, or diabolically smart criminal masterminds. Most are generally human. But one stands apart, the massive freak of nature known as Killer Croc. Born as Waylon Jones, Croc has a rare genetic condition which gives him a crocodilian appearance. Raised by an abusive aunt who mocked his deformity, he eventually ran away and joined the circus, becoming a sideshow carnival attraction, where patrons could come and gawk at the freakish strongman called "Killer Croc." Croc eventually departed for Gotham City, where he began a life of crime, one which brought him into regular conflict with the Dark Knight.