A Child of the '80s, Killer Croc first appeared in the pages of Detective Comics #523 and Batman #357 in 1983. Although Waylon Jones was originally depicted as basically just a scaly dude, over the years he has transformed into a much more reptilian form.
Killer Croc made his onscreen debut in the 1992 as a recurring villain on Batman: The Animated Series. In this depiction, Croc was given gray rather than green skin and was played as being kinda strong, and kinda dumb with a preference for smashing Batman with a rock.
Croc received a "greening" makeover for his appearances in 1998 on The New Batman Adventures. In the episode Love is a Croc, KC and Baby Doll made an unlikely and ultimately ill fated couple.
In 2000, the Batman Beyond episode Terry's Friend Dates a Robot, a robotic version of Killer Croc made a cameo appearance during a training session for the new Batman.
In 2005, Killer Croc returned to airwaves on The Batman. This Killer had taken a more croc-like appearance, sporting a tail and snout along with a Cajun accent.
The Batman: Gotham Knight direct to video made use of Killer Croc in 2008. Set as a bridge between Batman Begins and The Dark Knight the movie took Batman into the sewers where he encountered the mutated serial killer who, having been exposed to Scarecrow's fear toxins, was a formidable force for the Dark Knight.
In 2011, Killer Croc took a whupping from Captain Marvel in Bat-garb on Batman: The Brave and the Bold and in spite of his numerous appearances, old KC never really established himself as an A-list villain. Perhaps his next appearance will finally win him his big break.