The Rat Pack was a group of actors originally centered on Humphrey Bogart. In the mid-1960s it was the name used by the press and the general public to refer to a later variation of the group, after Bogart's death, that called itself "the summit" or "the clan," featuring Frank Sinatra, Dean Martin, Sammy Davis, Jr., Peter Lawford, and Joey Bishop, who appeared together on stage and in films in the early-1960s, including the movie Ocean's 11. Sinatra, Martin and Davis were regarded as the group's lead members. The name "Rat Pack" was first used to refer to a group of friends in New York. Several explanations have been offered for the famous name over the years. According to one version, the group's original "Den Mother," Lauren Bacall, after seeing her husband (Bogart) and his friends return from a night in Las Vegas, said words to the effect of "You look like a goddamn rat pack." "Rat Pack" may also be a shortened version of "Holmby Hills Rat Pack," a reference to the home of Humphrey Bogart and Lauren Bacall which served as a regular hangout.
Visiting members included Errol Flynn, Nat King Cole, Mickey Rooney and Cesar Romero.
According to Stephen Bogart, the original members of the Holmby Hills Rat Pack were Sinatra (pack master), Judy Garland (first vice-president), Bacall (den mother), Sid Luft (cage master), Bogart (rat in charge of public relations), Swifty Lazar (recording secretary and treasurer), Nathaniel Benchley (historian), David Niven, Katharine Hepburn, Spencer Tracy, George Cukor, Cary Grant, Rex Harrison, and Jimmy Van Heusen. In his autobiography The Moon's a Balloon, Niven confirms that the Rat Pack originally included him but not Sammy Davis Jr. or Dean Martin.