8th Missouri Cavalry Regiment was a cavalry unit from Missouri that served in the Union Army during the American Civil War. The regiment was formed between 6 August and 15 September 1862. The regiment fought at Prairie Grove and Van Buren in 1862. The unit participated in Frederick Steele's expedition to Little Rock in 1863, fighting at Brownsville, Bayou Meto, and Bayou Fourche. From 1863 to 1865, the regiment remained in Arkansas, going on expeditions to suppress Confederate raiders and other occupation duties. The unit was mustered out of service on 20 July 1865. In January 1863, the regiment committed what has become known as the Huntsville Massacre.