The USS T. D. Horner was a stern-wheel steamer built in 1859 at Brownsville, Pennsylvania and was part of Colonel Charles Ellet, Jr.'s United States Ram Fleet during the American Civil War.

The ship was purchased by the War Department on 18 May 1862 for use on the Mississippi River and its tributaries in the Army's newly established flotilla which was popularly known as the "Ellet Ram Fleet."

T. D. Horner served the Ram Fleet and its successor, the Mississippi Marine Brigade, as a tug until the latter was dissolved on 24 August 1864.

She was re-documented for merchant service on 27 November 1865 and plied the Mississippi and its tributaries until New Year's Day 1868 when she hit a bridge at Louisville, Kentucky, and was damaged beyond economical repair.

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.