Joker (Earth-203: Pre-Crisis)

"Knock knock, who's there? Batgirl, past tense!"

- The Joker after shooting Barbara Gordon

The Joker was a criminal in New Gotham and the archenemy of Batman.

Biography
At some point, the Joker became an enemy of Batman and fought him for many years alongside his assistant, Harley Quinn.

He eventually lost but was not killed by Batman which gave him the opportunity to send Clayface to kill Selina Kyle whilst masquerading as him.

He later went to Barbara Gordon's apartment and shot her causing her to be permanently paralyzed from the waist down. Soon after he was arrested.