Killer Croc (Gotham Knight)

"Eh...Killer Croc...they say his momma didn't want him, flushed him into the sewers..."

- A homeless person brings up Killer Croc's alleged origin Killer Croc (Real Name Waylon Jones), is a brutish super villain suffering from a rare skin condition that gives him reptilian scales. Having been driven mad by both abuse and Jonathan Crane's experiments, he works for Scarecrow in his kidnapping of a Gotham cardinal.

He appears in the collection of anime short films Batman: Gotham Knight, specifically the short "In Darkness Dwells".

History
Waylon Jones was born with a rare skin disorder that made him appear reptilian, and consequentially became a sideshow freak. One day tiring of this, he sharpened his teeth until they were like a set of fangs and went on a killing spree. This landed him in Arkham Asylum, where he was made a "patient" in Jonathan Crane's "fear aversion therapy". Ironically, Waylon's fear was of bats, and Crane performed unethical experiments on him in the name of making him overcome this fear.

Later, after the inmates of Arkham Asylum were freed and Jonathan Crane became the Scarecrow, Waylon as Killer Croc worked for him, helping him kidnap helpless people (such as a benevolent Gotham cardinal). When Batman gave pursuit, he followed Scarecrow and Croc into the sewers. Croc intercepted him and the two briefly fought before Batman drove him off. Killer Croc's fate afterwards is unrevealed.

trivia

 * Batman: Gotham Knight is supposed to be canon with the Christopher Nolan Batman films, but there are numerous things in the short films proper that contradict this claim, making it highly questionable just how compatible with the Nolan films Gotham Knight actually is.
 * Like other versions of the character, this Killer Croc eats people. However, in this case it is only allegedly so, as he is never actually shown to engage in cannibalism in the short film proper.