Salvatore 'Mooney' Giancana (born Gilormo Giangana; May 24, 1908 – June 19, 1975) was an American mobster who was boss of the Chicago Outfit from 1957 to 1966.

Giancana was born in Chicago to Italian immigrant parents. He joined the 42 Gang as a teenager, developing a reputation in organized crime, which gained him the notice of the leaders of the Chicago Outfit, which he joined during the late 1930s. From the 1940s through the 1950s, he controlled illegal gambling, illegal liquor distribution, and political rackets in Louisiana. In the early 1940s, Giancana was involved in a takeover of Chicago's black American lottery payout system for the Outfit. In 1957, he became the boss of the Chicago Outfit.

According to some sources, Giancana and the Mafia were involved in John F. Kennedy's victory in the 1960 presidential election. During the 1960s, he was recruited by the Central Intelligence Agency (CIA) in a plot to assassinate Cuban leader Fidel Castro. Conspiracy theorists consider Giancana, along with Mafia leaders Santo Trafficante Jr. and Carlos Marcello, to be associated with the assassination of John F. Kennedy. In 1965, Giancana was convicted of contempt of court, serving one year in prison. After his release from prison, Giancana fled to Cuernavaca, Mexico. In 1974, he was deported to the United States, returning to Chicago.

Giancana was murdered on June 19, 1975, at his home in Oak Park, Illinois, shortly before he was scheduled to appear before the Church Committee.