Jason Todd (Earth-1: Post-Crisis)

"Croc was briefly in competition with a small army of Batman villains under the leadership of the Joker. But in his time as a crime boss, Croc employed such experienced henchmen as the Riddler and Penguin. Of his list of atrocities, the murder of Joseph and Trina Todd is notable, as their deaths inspired their adoptive son Jason to take up the costumed role of the second Robin."

- Killer Croc's A.R.G.U.S. File

Jason Todd is the vigilante known as Robin.

Early Life
At some point, Jason Todd was adopted by Joseph and Trina Todd. Following their murder by Killer Croc, Jason became a vigilante, becoming the second individual to use the codename of Robin.