Waylon Jones (Earth-Prime)

"Joker's acid flower. Clayface's mud, Killer Croc's tooth. Why you collecting all this stuff from Batman's enemies? So I can succeed where they failed."

- Russell Tavaroff and Black Mask

Killer Croc was an enemy of Batman and a patient at Arkham Asylum.

Biography
At some point, Killer Croc became an enemy of Batman before being defeated and locked in Arkham Asylum. Afterwards, Batman kept his tooth in the Batcave until it was stolen in 2021 by "Circe Sionis" and given to Black Mask.

Powers

 * Unique Physiology: Killer Croc has a unique physiology, as shown by his tooth resembling a fang rather than a regular human tooth.