Name: Jack O'Leary
Number of Appearances: 1
Enemy of: Superman
Note: boss of illegal numbers rackets in Metropolis
Superman was waging war against gambling in Metropolis. The hero caught a barber running an illegal numbers racket out of his barbershop. He threatened to kill the barber unless he revealed who was "the boss of the numbers racket in this town." The barber told him, "Jack O'Leary is the man you want. He's got the numbers racket under his thumb in this town. Every petty operator pays off to him!"
Superman spent the rest of the story taking down O'Leary's operation specifically and Metropolis gambling generally.
After learning O'Leary name, Superman went directly to his home, barged in past the butler, and threatened the criminal. Superman forced O'Leary to give him the addresses of all gambling joints he had connections to. Over the next few hours, Superman wrecked every one of them. Some operators of the illegal gambling dens called the police, but the police just laughed and cheered for Superman.