Caspar, Johnny (Miller's Crossing)- Johnny Caspar is the boss of the rival Italian gang. Caspar’s Italian gang is in a city run by Irish gang boss Leo O'Bannon. Caspar wants to kill crooked bookie Bernie Bernbaum for sabotaging his fixed boxing matches but is denied by O’Bannon. Johnny decides to declare war on O’Bannon and eventually forces Leo underground, taking over the city and "runnin' things" himself. Johnny is even assisted and advised by O’Bannon’s longtime friend, Tom Regan, who used to work for Leo until they had a falling out over Bernie's sister, Verna. Unfortunately, Johnny soon discovers that "runnin' things ain't all gravy." Caspar discovers that his strong beliefs in loyalty, "friendship, character and ethics" mean nothing in a world where everyone only looks out for themselves.

Tom tries to convince Verna and Leo to give Bernie up to Caspar so that he will end the war, but neither of them will budge. After an assassination attempt on Leo, Tom reveals his affair with Verna, causing Leo to beat up Tom and turn his back on him and Verna. Because of the lack of loyalty that Tom has recently experienced, Tom goes to work for Caspar. Caspar immediately instructs Tom to kill Bernie at Miller's Crossing to prove his loyalty to him.

Bernie pleads with Tom to not kill him, and Tom allows him to escape. The gang war is going Caspar’s way and he quickly becomes the boss of the city. Unknowingly to Caspar, Tom begins encourage disputes between Caspar and his most trusted man, Eddie Dane. At the same time, Bernie returns and tries to blackmail Tom into killing Caspar.

Tom's betrayal convinces Caspar to kill Eddie Dane. Tom arranges a meeting with Bernie, but sends Caspar instead. To Caspar’s surprise, Bernie shows up and kills him.

Johnny Caspar in Miller’s Crossing in played by Jon Polito.