10) He First Appeared In The 80s
Most of the bigger figures in Batman’s rogues gallery come from the earlier half of the character’s history, but Killer Croc is a relatively recent addition (even though he’s ten years older than Harley Quinn).
Created by Gerry Conway and Don Newton, the cannibalistic crocodile made his first proper appearance in Batman #357 in 1983. However, he’d been set up in a previous comic, Detective Comics #523, as a shadowy figure waiting in the wings.
Initially, he was presented as taking over as mob boss from dead hoodlum the Squid. Naturally, a certain flying rodent man puts paid to that career turn. While he was still recognizably Croc as we know him, it was only later stories that would explore his more savage side and his sympathetic origins.