"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, Frank Sinatraand others who met casually at the Holmby Hills home of Humphrey Bogart and Lauren Bacall.

"In the 1960s, the group featured Frank Sinatra, Dean Martin, Sammy Davis Jr., Joey Bishop, and (before falling out with Sinatra in 1962) 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."

- Wikipedia (online April 2022)