Samuel Osborne Barber II (March 9, 1910 – January 23, 1981) was an American composer of orchestral, opera, choral, and piano music. He is one of the most celebrated composers of the 20th century: music critic Donal Henahan stated that "Probably no other American composer has ever enjoyed such early, such persistent and such long-lasting acclaim."

His Adagio for Strings (1936) has earned a permanent place in the concert repertory of orchestras. He was awarded the Pulitzer Prize for Music twice: for his opera Vanessa (1956–57) and for the Concerto for Piano and Orchestra (1962). Also widely performed is his Knoxville: Summer of 1915 (1947), a setting for soprano and orchestra of a prose text by James Agee. At the time of his death, nearly all of his compositions had been recorded.