Media term for an informal group of entertainers centered on the Las Vegas casino scene in the 1960s
The so-called Rat Pack wasn't a group in the normal sense, but consisted of a loose confederation of actors, comedians, and singers lumped together by the media under that name in the early '60s. Frank Sinatra, Dean Martin, Sammy Davis Jr., Joey Bishop, and Peter Lawford formed the core of the Rat Pack, and they appeared together in several movies, including Robin and the Seven... Wikipedia