William Allen Trimble (April 4, 1786 - December 13, 1821) was a National Republican politician from Ohio. He served in the U.S. Senate.

Born in Woodford, Kentucky, Trimble attended Transylvania College. He briefly practiced law in Highland County, Ohio in 1811-1812. In the subsequent years he served in a variety of capacities, mostly in Indian campaigns, with the Ohio militia and U.S. Army. He was a major of the Ohio Volunteers 1812; major of the Twenty-sixth United States Infantry 1813; raised to lieutenant colonel in 1814; lieutenant colonel of the First United States Infantry 1814; transferred to the Eighth United States Infantry 1815 and resigned in 1819, after being elected to the United States Senate in 1818. Trimble served in the Senate until his death three years later.