Peter Lawrence Frederick Heyworth (21 June 1921 - 2 October 1991) was an American-born English music critic and biographer. He wrote the definitive biography of Otto Klemperer and was a prominent supporter of avant-garde music.
He was the music critic for the Times Educational Supplement from 1952 to 1956 and the music critic of The Observer (London) from 1955 to 1988. He was the author of Conversations with Klemperer (1973) and Otto Klemperer: His Life and Times (2 vols, 1983-1996; 2nd vol completed by John Lucas). The Klemperer biography stands as a literary achievement of merit having, precision, sympathy, psychoanalytic depth and breadth of scope.