A Backing vocalist provides harmony with their voice.
Peter Sydney Ernest Lawford -LRB- born Peter Sydney Ernest Aylen ; 7 September 1923 -- 24 December 1984 -RRB- was a British actor who lived in the United States throughout his adult life .. He was a member of the `` Rat Pack '' and brother-in-law to President John F. Kennedy .. Rat Pack. Rat Pack. John F. Kennedy. John F. Kennedy. In later years , he was noted more for his off-screen activities as a celebrity than for his acting .. From the 1940s to the 1960s , he had a strong presence in popular culture and starred in a number of highly acclaimed films .