Robert Kelmsley (Robin) Orr CBE (2 June 1909 - 9 April 2006) was a Scottish composer.
Born in Brechin, and educated at Loretto School, he studied at the Royal College of Music in London and at Pembroke College, Cambridge where he studied under Cyril Rootham. Following studies with Alfredo Casella and Nadia Boulanger he returned to Cambridge in 1938 as Organist of St John's College. During his war service Herbert Howells deputized for him. After World War II he became a lecturer at Cambridge and a professor at the Royal College of Music, then Gardiner Professor of Music at Glasgow University from 1956 to 1965. He was succeeded in this role in 1966 by Prof Fred Rimmer.
He returned to Cambridge in 1965 as Professor of Music, a post he held until his retirement in 1976 (later Emeritus). He was made a CBE in 1972. He was not related to Buxton Orr (1924-1997) - also a Scottish composer.
His works include three operas: Full Circle (STV for Scottish Opera, 1968), Hermiston (Edinburgh Festival 1975) and On the Razzle (RSAMD 1988), three Symphonies, and the Sinfonietta Helvetica (1990), alongside church music and solo and chamber works.