Judith Exner (January 11, 1934 – September 24, 1999) was an American woman who claimed to be the mistress of U.S. president John F. Kennedy and Mafia leaders Sam Giancana and John Roselli. She was also known as Judith Campbell Exner.
She was born Judith Eileen Katherine Immoor to a family of a German architect in New York. Her older sister Jacqueline (b. 1931) later became an actress and took the professional name Susan Morrow. Her family moved to Los Angeles when she was a child. She married actor William Campbell in 1952, but divorced him in 1958 when she became involved with Frank Sinatra. An alternative account states that they divorced in 1959, but after having been separated for two years.
On February 7, 1960, Sinatra introduced Exner to John F. Kennedy in Las Vegas when Kennedy was still a senator and a presidential candidate. She claimed to have become one of JFK's mistresses. Presumably, Jacqueline Kennedy was aware of the affair. Later, Sinatra introduced Exner to "Sam Flood", who was actually Sam Giancana. She later claimed that she had not known about his involvement with the Mafia before Kennedy asked her to contact Giancana on his behalf.