Percy William Whitlock (1 June 1903, Chatham, Kent – 1 May 1946, Bournemouth) was an English organist and composer. A student of Vaughan Williams at London's Royal College of Music, Whitlock quickly arrived at an idiom which combined elements of his teacher's output and that of Elgar. The result was immediately striking, particularly since his lush harmonic style also bore traces of Gershwin and other popular composers of the 1920s. Like Vaughan Williams and Delius, he often used themes that sounded like folksongs but were, in fact, original creations. Stanford, Quilter and Rachmaninov are other important stylistic influences.

From 1921 to 1930 Whitlock was assistant organist at Rochester Cathedral, Kent. Later (1930-1935) he served as music director at St Stephen's Anglican Church, Bournemouth, combining this from 1932 with the role of that town's borough organist, in which capacity he regularly played at the local Pavilion Theatre. After 1935 he worked for that theatre full-time. A tireless trainspotter, he wrote at length and with skill about his hobby. Sometimes, for both prose and music, he used the pseudonym Kenneth Lark. He worked closely with the Bournemouth Municipal Orchestra and gave dozens of live BBc broadcasts between 1933-46.

Among Whitlock's organ works are Five Short Pieces (1929), Four Extemporisations (1933; these are actually much more cogent than their title suggests), Seven Sketches on Verses of the Psalms (1934), the Plymouth Suite and — perhaps his masterpiece — the Sonata in C minor(1936). His Symphony in G minor for organ and orchestra was revived by Graham Barber and the BBC Welsh Symphony Orchestra in 1989 and has subsequently been recorded by Francis Jackson and the University of York Symphony Orchestra and received several concert performances. Whitlock's gifts expressed themselves most convincingly in the smaller forms, and as a miniaturist he can stand alongside many composers much better remembered than himself.

While only in his 20s Whitlock was diagnosed with tuberculosis; he also suffered from hypertension, and near the end of his life he lost his sight altogether. His early death, a few weeks before his 43rd birthday, deprived English music of a refreshing voice. For decades afterwards he remained largely forgotten. This neglect has eased in recent times, with the increased popularity of romantic and postromantic organ literature; his oeuvre's representation on compact disc continues to grow.

The Percy Whitlock Trust, founded in 1983, aims to make the composer's output better known. It co-ordinates many events and recitals, and publishes articles and features which relate to the composer. President of the Trust is Dr Francis Jackson CBE. The Trust Secretary is Malcolm Riley, who published the authorised biography of Percy Whitlock in 1998 and who followed it up with The Percy Whitlock Companion in 2007.