Sinatra was also part of the Rat Pack, a group of entertainers (musicians and actors), in the 1950s and 1960s. The name was informal, and the group was not an official organization of any sort, but a group of friends. Members of the Rat Pack included Sinatra, Dean Martin, Sammy Davis, Jr., Peter Lawford, and Joey Bishop, as well as (more loosely) Humphrey Bogart, Judy Garland, Lauren Bacall, Sid Luft, and Shirley MacLaine.