Henry Warren Smith (1837-1869) was a Union Army captain who served in the American Civil War. Smith served as a captain in the Adjutant General's Office in Washington DC during the American Civil War. On 17 April 1865, three days after the shooting of President Abraham Lincoln and the attempted murder of Secretary of State William H. Seward, Smith raided the Surratt Boarding House in Washington and arrested Mary Surratt and Lewis Powell. He later testified at Surratt's trial, resulting in the hanging of Surratt, Powell, and two other co-conspirators on 7 July 1865. By then, Smith had been transferred to Vicksburg, Mississippi to work with the Freedmen's Bureau, and he served in the US 3rd Cavalry Regiment until his death at Fort Stanton, New Mexico Territory in 1869.