The Rat Pack was an informal group of entertainers, the second iteration of which ultimately made films and appeared together in Las Vegas casino venues. They originated in the late 1940s and early 1950s as a group of A-list show business friends, such as Errol Flynn, Nat King Cole, Mickey Rooney, Judy Garland, Frank Sinatra and others who met casually at the Holmby Hills home of Humphrey Bogart and Lauren Bacall. In the 1960s, the group featured Sinatra, Dean Martin, Sammy Davis Jr., Joey Bishop, and Peter Lawford, among others. They appeared together on stage and in films in the 1950s and 1960s, including the films Ocean's 11 and Sergeants 3; after Lawford's expulsion, they filmed Robin and the 7 Hoods with Bing Crosby in what was to have been Lawford's role. Sinatra, Martin, and Davis were regarded as the group's lead members after Bogart's death.

Francis Albert Sinatra was an American singer and actor. Nicknamed the "Chairman of the Board" and later called "Ol' Blue Eyes", he is regarded as one of the most popular entertainers of the mid-20th century. Sinatra is among the world's best-selling music artists, with an estimated 150 million record sales globally.