Jack "Legs" Diamond
- The novel's protagonist, he is a ruthless gangster who has built an underground empire based on bootlegging, drug dealing, and money laundering. Although he has a business-wise mean streak, Jack does not relish violence. His vibrant personality has made it easy for the press and others to see him as a larger- than-life bad guy. Jack loves his wife, but he also loves his girlfriend.
- The novel's narrator, he is an Albany lawyer who ends up representing the infamous New York gangster, Jack Diamond. The novel consists of Marcus's recollections of Jack and Jack's legacy. Marcus is cocky and confident that Jack's myth deserves its place in the book of American legends. The most exciting spell of Marcus's life came when he worked for Jack Diamond.
in-depth analysis of Marcus Gorman.
- Jack's faithful wife, she is the archetypal good homemaker. She cooks for Jack and keeps his house well furnished. Troubled by Jack's corrupt occupation, Alice surrounds him with reminders of his Irish Catholic heritage. Deep down, though, Alice has a small ruthless streak.
in-depth analysis of Alice Diamond.
Marion "Kiki" Roberts
- Jack's girlfriend, she is a stereotypical Broadway dancer. She has a perfect body and knows how to wield her sex appeal, but is not exceptionally intelligent and she can't cook, either. She loves to party and hates being left alone when Jack has to do business or go home to his wife.
- Jack's brother, he was Jack's closest companion. They got into the life of crime together when they started stealing bootleg booze. Jack thinks that Eddie brought him good luck. Eddie died of tuberculosis before most of the events in this novel take place.
Joe "Speed" Fogerty
- Jack's driver and right-hand man, he is the spitting image of Eddie. Fogerty carries around Eddie's revolver and essentially provides a replacement for Jack's brother. Fogerty does not like to fight, so Jack rarely asks him to strong-arm anyone, and Fogerty usually leaves Eddie's .38 millimeter gun unloaded.
Murray "The Goose" Pucinski
- A short but stocky man with an eye patch, he is Jack's strong man. The Goose is the guy Jack calls to do his dirty work. They met in the army when they were both in prison. During an argument,Jack punched out Goose's eye, which is why Goose wears an eye patch.
- Another figure of the New York underworld, he owns a farm that Jack rents and uses to make and store booze. Not a particularly pleasant fellow, Biondo is a partner of sorts with Jack until Jack refuses to return the money that Biondo loaned him to make a drug deal.
- A local upstate bumpkin, he happens to be moving a small truck of hard cider as Jack drives by one evening. Streeter is taken to Jack's farm and tortured so that he will reveal the location of his sill. This incident leads directly to the stepped-up statewide effort to catch Jack.
- The Jewish mob boss under whom Jack begins his tutelage. When Rothstein tells Jack that he needs a new haircut, Jack murders and robs a man to pay for one.
- An underworld figure who provides Jack with financial support when Jack is down and out.
- Owner of a favorite latter-day Diamond hangout, The Parody Club, he is an Irish American barkeep who does a few favors for Jack. At the beginning of the novel, Marcus and Packy reminisce about Jack.
- A fun-loving hooker with the proverbial heart of gold. She sleeps with both Jack and Marcus and is a mainstay at the Parody Club, where she sings as well as sells her body.