Gustavus Adolphus Smith (December 26, 1820 – December 11, 1885) was a prosperous carriage maker in Decatur, Illinois before the American Civil War. He was a volunteer Union Army colonel from the beginning of the war until September 22, 1863 and from February 28, 1865 until December 14, 1865. After the end of the war, on January 13, 1866, President Andrew Johnson nominated Smith for appointment to the grade of Brevet brigadier general of volunteers, to rank from March 13, 1865. The United States Senate confirmed the appointment on March 12, 1866. Starting in 1870, Smith was a collector of internal revenue in New Mexico.