Alexander Early Steen (1827 – December 7, 1862) was a career American soldier from Missouri who served in the United States Army in the Mexican–American War. He rejoined the army in 1852 and served until he resigned to join the Confederate forces on May 10, 1861. He served as a general in the secessionist Missouri State Guard forces and as a colonel and acting brigadier general in the Confederate States Army during the American Civil War. He was killed in the Battle of Prairie Grove.