American poet, biographer, and novelist who had a great impact on popular literature with his historical novel Anthony Adverse.

Allen's first published work was a book of poetry, Ballads of the Border (1916). During the 1920s he established a reputation as a poet, publishing several more volumes of verse.

Allen was wounded in World War I; the novel Toward the Flame (1926) came out of his wartime experience. That same year his authoritative biography Israfel: The Life and Times of Edgar Allan Poe was published.

In 1933, after five years of writing, he published Anthony Adverse, which was a huge success. Set in Europe during the Napoleonic era, Anthony Adverse offered a multitude of characters and picturesque settings within a complex plot. The book's undisguised passages about sex and its considerable length introduced a new standard for popular fiction.

Allen's following novels did not attain the popularity or the critical acclaim of Anthony Adverse, although the first three volumes of his planned five-volume series about colonial America (The Forest and the Fort, 1943; Bedford Village, 1944; Toward the Morning, 1948) were widely read. Allen was at work on the fourth volume of the series (The City in the Dawn; published posthumously, 1950) at the time of his death.