Sir Reginald Sparshatt Thatcher OBE MC MusDoc FRCM FRCO (born Midsomer Norton, Somerset, 11 March 1888, died Cranleigh, Surrey, 6 May 1957) was a composer and the Principal of the Royal Academy of Music.
He was the son of a brewer at Welton, Midsomer Norton, and one of fifteen children. He was educated privately and at the Royal College of Music and Worcester College, Oxford, where he was organ scholar, and took a doctorate; he was also FRCO. He was assistant master, Clifton College, Bristol from 1911-14. In World War I he was awarded the Military Cross. He became director of music at the Royal Naval College, Osborne. He was director of music at Charterhouse School from 1919–28 and Harrow School from 1928-36. He then became deputy director of music at the BBC from 1937–44, and then warden, vice-principal and finally principal of the Royal Academy of Music from 1949–1955.
He was the composer of the hymn, 'Come ye faithful'.
Portraits of him by Walter Stoneman and Elliott & Fry hang in the National Portrait Gallery, London. His portrait has also been painted by Rodrigo Moynihan.