William Elisha Haynes (October 19, 1829 – December 5, 1914) was an American Civil War veteran who served two terms as a U.S. Representative from Ohio from 1889 to 1893.

Born in Hoosick Falls, New York, Haynes moved to Ohio with his parents, who settled in Lower Sandusky (now Fremont) in 1839.

Enlisted in the Union Army as a private April 16, 1861, in the Eighth Regiment, Ohio Volunteer Infantry.

Commissioned captain and served in western Virginia, the Shenandoah Valley, and in the Army of the Potomac until November 1862, when he was commissioned lieutenant colonel of the Tenth Regiment, Ohio Volunteer Cavalry, and served with it in the Army of the Cumberland until 1864, when he was honorably discharged.

[2] This article incorporates public domain material from the Biographical Directory of the United States Congress