McDowell, Irvin (1818–1885), a United States army officer. McDowell was born in Columbus, Ohio. He graduated from West Point in 1838 and served with distinction during the Mexican War. At the start of the Civil War he was made brigadier general of volunteers and given command of the Union army south of the Potomac River. McDowell's ill-trained troops lost the First Battle of Bull Run (1861), the first battle of the war. After the battle he was replaced by Major General George B. McClellan.

McDowell was a corps commander at the Second Battle of Bull Run (1862), another Confederate victory. He was relieved of his command and never again appeared in battle, though a court of inquiry cleared him of misconduct. McDowell commanded various military departments after 1864. He retired in 1882 as a major general.