Robert Thompson Van Horn (May 19, 1824 – January 3, 1916) was a lawyer, the owner and publisher of The Kansas City Enterprise, mayor of Kansas City, Missouri during the parts of the Civil War, member of the Missouri General Assembly, and representative to the Forty-seventh Congress of the United States.
Born in East Mahoning Township, Indiana County, Pennsylvania to Henry and Elizabeth (Thompson) Vanhorn, he moved to Pomeroy, Ohio in 1844, studied law and was admitted to the bar about 1850.
He moved to Kansas City in 1855, was a member of the board of aldermen in 1857; postmaster of Kansas City 1857–1861 Van Horn purchased the newspaper The Enterprise in 1856 and renamed it The Kansas City Journal, which published daily from 1858 until its closing in 1942.
Van Horn was elected mayor of Kansas City to three terms, in 1861, 1863, and 1864.
He enlisted in the Union Army during the American Civil War and served as lieutenant colonel of the Twenty-fifth Regiment, Missouri Volunteer Infantry; member of the Missouri State Senate 1862–1864; elected as a Republican to the Thirty-ninth, Fortieth, and Forty-first Congresses (March 4, 1865 – March 3, 1871); was not a candidate for renomination in 1870; chairman of the Republican State central committee 1874–1876; collector of internal revenue for the sixth district of Missouri 1875–1881. In 1882, he was one of the original incorporators of the Kansas City Club.