Gordon Percival Septimus Jacob CBE (5 July 1895 – 8 June 1984) was an English composer and teacher. He was a professor at the Royal College of Music in London from 1924 until his retirement in 1966, and published four books and many articles about music. As a composer he was prolific: the list of his works totals more than 700, mostly compositions of his own, but a substantial minority of orchestrations and arrangements of other composers' works. Those whose music he orchestrated range from William Byrd to Edward Elgar to Noël Coward.