British historian and biographer particularly noted for his three-volume life of Samuel Pepys (1933, 1935, 1938). His histories have an epic sweep that gained them popular readership. Typical of his approach is the panoramic view of English history he began during World War II with The Years of Endurance, 1793–1802 (1942) and Years of Victory, 1802–1812 (1944) and continued with The Age of Elegance, 1812–1822 (1950).

Bryant left his studies at Harrow at 18 to become one of the early pilots in the Royal Air Force in World War I. After graduation from Oxford, he became principal of the Cambridge School of Arts, Crafts and Technology (1923–25) and then history lecturer in Oxford's extra-mural studies department (1925–36). His first works were biographies of King Charles II (1931) and Macaulay (1932). His interest in United States history is revealed in The American Ideal (1936). Among his other biographies are George V (1936), Stanley Baldwin (1937), Nelson (1970), and The Great Duke (i.e., Wellington; 1971). Later histories include A Thousand Years of British Monarchy (1975) and The Spirit of England (1982). He was knighted in 1954.