Percy William Allen (2 July 1895 – 21 October 1969) was an English professional footballer who played predominantly as a right half. He was born in West Ham, Essex. A Lieutenant, Allen served in the British Army during World War I, and played as an amateur before moving to West Ham United for the club's initial Division Two season. Having played for the club three times in the London Combination between December 1917 and October 1918, he made his full debut in a 2–1 home defeat to Birmingham on 1 November 1919, at outside-right. He was also played at centre-forward, but became an ever-present at right-half during the 1921–22 season. Allen lost his place in the team to Sid Bishop due to the reappearance of a blood ailment which he had suffered from during his time in the Army.