Percy Stafford Allen was born on July 7, 1869, in Twickenham, England.

He was a British classical scholar best known for his writings on Desiderius Erasmus. He received his early education in Rottingdean. From 1882, he studied Latin and Greek at Clifton College and, after 1888, at Corpus Christi College, Oxford (B.A., 1892; M.A., 1896). From 1897 to 1901, he taught history at Government College in Lahore, British India (now Pakistan). He returned to Oxford in 1908 as a Fellow of Merton College, Oxford. From 1924 to 1933, he was president of Corpus Christi College. In 1925, he delivered the British Academy's Master-Mind Lecture on "Erasmus' Services to Learning." In 1928, Allen became a foreign member of the Royal Netherlands Academy of Arts and Sciences. He was the editor of the complete letters of Erasmus of Rotterdam (12 volumes). He also published “The Age of Erasmus: Lectures,” delivered at the University of Oxford and London (1914), and “Letters of Richard Fox, 1486–1527” (1929).

In 1898, he married Helen Mary Allen (1872–1952), who made significant contributions to their scholarly collaborations and was acknowledged through several honours: she received honorary doctorates from the University of Basel (1946) and the University of Amsterdam (1948), as well as an honorary M.A. degree from Oxford (1932). Allen died on June 16, 1933, in Oxford, England.