William E. Hart (1843 – October 21, 1874) was a Union Army soldier during the American Civil War. He received the Medal of Honor for gallantry during the Valley Campaigns of 1864 & 1865. Hart was instrumental in the capture of Confederate cavalry raider Colonel Harry Gilmor on February 4, 1865. Hart enlisted in the Army from Rushville, New York in October 1861, and mustered out with his regiment in June 1865.