Percy William Whitlock (1 June 1903, Chatham, Kent – 1 May 1946, Bournemouth) was an English organist and post-romantic composer.

A student of Vaughan Williams at London's Royal College of Music, Whitlock quickly arrived at a musical idiom that combined elements of his teacher's output and that of Elgar. His lush harmonic style also bore traces of Gershwin and other popular composers of the 1920s. Stanford, Rachmaninov and Roger Quilter are other important stylistic influences. Like Vaughan Williams and Frederick Delius, he often used themes that sounded like folk songs but were, in fact, original creations.

From 1921 to 1930 Whitlock was assistant organist at Rochester Cathedral in Kent. He served as Director of Music at St Stephen's Church, Bournemouth for the next five years, 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 the Pavilion 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 (1937–1939) and 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 subsequently recorded by Francis Jackson and the University of York Symphony Orchestra. Nevertheless, Whitlock's gifts expressed themselves most convincingly in the smaller forms, and as a miniaturist he can stand alongside many better remembered composers.

Whitlock was diagnosed with tuberculosis in his twenties, and also suffered from hypertension. Near the end of his life he lost his sight altogether, and he died a few weeks before his 43rd birthday. For decades afterwards he remained largely forgotten. This neglect has eased in recent times with the increased popularity of post-romantic organ literature.

The Percy Whitlock Trust, founded in 1983, coordinates many events and recitals. The 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.