Samuel J. Kirkwood (December 20, 1813 - September 1, 1894), was an American politician.
Born in Harford County, Maryland, he twice represented Iowa as a United States Senator; first, from 1866 to 1867 and again from 1877 to 1881. Kirkwood first held statewide office as Governor of Iowa from 1860 to 1864. Between his separate terms as a Senator, he was again the Governor of Iowa from 1876 to 1877. He resigned as Governor in 1877 to begin his second term as U.S. Senator. In 1881, Kirkwood resigned his Senate seat to become Secretary of the Interior under President James Garfield. He served as Interior Secretary until 1882. He ran for president in 1886.
Kirkwood was a member of the Republican party. Kirkwood Community College in Cedar Rapids, Iowa is named for the former Iowa Governor and Senator. He was probably a cousin of astronomer Daniel Kirkwood.
Kirkwood died in 1897 in Iowa City, Iowa and is buried in Oakland Cemetery in Iowa City.