Created by Gerry Conway, Don Newton and Gene Colan, the character was introduced in Detective Comics #523 (February 1983).

The character has also been a member of the Suicide Squad, debuting in the fifth volume of the comic series revolving around the team, and a romantic interest of Enchantress.

Killer Croc made his live-action debut in the 2016 DC Extended Universe film Suicide Squad, portrayed by Adewale Akinnuoye-Agbaje.

[3] Waylon Jones was born with a rare form of atavism that imparted him with reptilian traits with his birth causing the death of his mother.

In these original, Pre-Crisis appearances, Killer Croc resembled a powerfully built man covered entirely in green scales, but was still basically human in his facial proportions and build.

Batman follows him there, only to find that the mysterious force is actually the Swamp Thing, who offers Croc a place in the swampland where he can finally give in to his animal side, live free from human persecution and have a peaceful and joyous life.

When an attempt at a cure fails, Killer Croc devours the involved doctor and retreats to the sewers, vowing vengeance on Batman and Black Mask.

[10] He next shows up in Countdown where he breaks free from his shackles in Arkham Asylum and attempts to kill Jimmy Olsen, who uses elastic powers to escape.

During the "Final Crisis" storyline, Killer Croc can be seen as the member of Libra's Secret Society of Super Villains.

[13] In the "Battle for the Cowl" storyline, Killer Croc is recruited by a new Black Mask to be a part of a group of villains aiming to take over Gotham and Bludhaven.

During the events of Brightest Day, Killer Croc is intentionally released from his cell by a guard whom Osiris kills when Deathstroke and his band of Titans infiltrate Arkham.

[14] In the continuity of DC's 2011 reboot The New 52, Killer Croc is established to have fought Roy Harper in Hell's Kitchen in a flashback seen in Red Hood and the Outlaws.

[volume & issue needed] While institutionalized in Arkham, Killer Croc meets Sybil Silverlock, a woman with dissociative identity disorder.

[17] He recently helped Harley Quinn and her friends fight a gang of other Batman villains in Coney Island.

Killer Croc and June Moone enjoy New York City and decide to explore their romance in the future.

Enchantress's rampage in New York City lasts until it is revealed that it is an editor from a magazine company who rejected June.

In Infinite Frontier, Killer Croc, Firefly, Knockout, and Cheshire are brought together by Clayface as potential allies hoping to seek a second chance by defending Allytown.

Red Hood is on a mission to track down Bane until Croc goes after him for ruining his operation and costing him millions of dollars.

Croc, along with Man-Bat, the Orca and the Terrible Trio kidnap a doctor at Gotham Zoo, and encounter Batman and Robin.

He decides to quit and check on Poison Ivy, whom Croc helps escape from a collapsing abandoned building.

Killer Croc's backstory explains that he was born with a condition resembling epidermolytic hyperkeratosis, a disfiguring skin disorder.

However, it is actually a form of regressive atavism, meaning that he has inherited traits of ancestral species of the human race, such as reptiles.

His skin is hardened to the degree that it is nearly impenetrable to ordinary forms of abrasion or penetration, including high caliber weapons fired from a distance.

He also possesses an extraordinary amount of super-strength; for example, he was able to tear a bank vault door off of its hinges with minimal effort.

As a result of these feelings of jealousy, Croc will often entertain himself by grabbing hold of small, pointy objects as a source of comfort.

This is a departure from his initial portrayal, where he was shown to be a ruthless and intelligent criminal who was able to plot his ascent from henchman to The Squid to perhaps the most powerful force in Gotham organized crime before being defeated by the Batman.

When Mattel got the license to make DC products in the early 2000s, they released their own version of Killer Croc, sculpted by Four Horsemen Studios.