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 "The 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.

Francis Albert "Frank" Sinatra,  /sɨˈnɑːtrə/, (December 12, 1915 – May 14, 1998) was an American singer and film actor.

Beginning his musical career in the swing era with Harry James and Tommy Dorsey, Sinatra became an unprecedentedly successful solo artist in the early to mid-1940s, after being signed to Columbia Records in 1943. Being the idol of the "bobby soxers", he released his first album, The Voice of Frank Sinatra in 1946. His professional career had stalled by the 1950s, but it was reborn in 1953 after he won the Academy Award for Best Supporting Actor for his performance in From Here to Eternity.

He signed with Capitol Records in 1953 and released several critically lauded albums (such as In the Wee Small Hours, Songs for Swingin' Lovers, Come Fly with Me, Only the Lonely and Nice 'n' Easy). Sinatra left Capitol to found his own record label, Reprise Records in 1961 (finding success with albums such as Ring-a-Ding-Ding!, Sinatra at the Sands and Francis Albert Sinatra & Antonio Carlos Jobim), toured internationally, was a founding member of the Rat Pack and fraternized with celebrities and statesmen, including John F. Kennedy. Sinatra turned 50 in 1965, recorded the retrospective September of My Years, starred in the Emmy-winning television special Frank Sinatra: A Man and His Music, and scored hits with "Strangers in the Night" and "My Way".

Dean Martin (born Dino Paul Crocetti; June 7, 1917 – December 25, 1995) was an American singer, film actor, television star and comedian. Martin's hit singles included "Memories Are Made of This", "That's Amore", "Everybody Loves Somebody", "You're Nobody till Somebody Loves You", "Sway", "Volare" and "Ain't That a Kick in the Head?". Nicknamed the "King of Cool", he was one of the members of the "Rat Pack" and a major star in four areas of show business: concert stage/night clubs, recordings, motion pictures, and television.

Martin was born in Steubenville, Ohio, to Italian parents, Gaetano and Angela Crocetti (née Barra). His father was from Montesilvano, Pescara, Abruzzo, Italy, and his mother was an Italian of part Neapolitan and part Sicilian ancestry. Martin was the younger of two sons. His brother was named Bill. Martin spoke only Italian until he started school. He attended Grant Elementary School in Steubenville, and took up the drums as a hobby as a teenager. He was the target of much ridicule for his broken English and ultimately dropped out of Steubenville High School in the 10th grade because he thought that he was smarter than his teachers. He delivered bootleg liquor, served as a speakeasy croupier, was a blackjack dealer, worked in a steel mill and boxed as welterweight. He grew up a neighbor to Jimmy the Greek.

Samuel George "Sammy" Davis Jr. (December 8, 1925 – May 16, 1990) was an American entertainer and was also known for his impersonations of actors and other celebrities.

Primarily a dancer and singer, Davis started as a child vaudevillian who became known for his performances on Broadway and Las Vegas. He went on to become a world famous recording artist, television and film star. Davis was also a member of Frank Sinatra's "Rat Pack".

At the age of three Davis began his career in vaudeville with his father and "uncle" as the Will Mastin Trio, toured nationally, and after military service, returned to the trio. Davis became an overnight sensation following a nightclub performance at Ciro's after the 1951 Academy Awards. With the trio, he became a recording artist. In 1954, he lost his left eye in an automobile accident.

His film career began as a child in 1933. In 1960 he appeared in the first Rat Pack film, Ocean's 11. After a starring role on Broadway in 1956's Mr Wonderful, Davis returned to the stage in 1964's Golden Boy, and in 1966 had his own TV variety show, The Sammy Davis Jr. Show. Davis' career slowed in the late sixties, but he had a hit record with "The Candy Man", in 1972, and became a star in Las Vegas earning him the nickname Mister Show Business.