William Allen (1803-July 11, 1879) was a Representative and Senator from Ohio and Governor of Ohio.
Allen was born in North Carolina. His sister, Mary Granberry Allen, married Pleasant Thurman, and their son, Allen G. Thurman, followed in his uncle's footsteps, becoming a lawyer and politician. Allen moved to Chillicothe, Ohio in 1819 and he and his sister lived there together.
He served as a Representative from Ohio from 1832 to 1834 and Senator from Ohio from 1837 to 1849.
He served as Governor of Ohio from 1874 to 1876.