William Windom (May 10, 1827 - January 29, 1891) was an American politician. He served in the United States House of Representatives and United States Senate as a Republican from Minnesota. He was born in Belmont County, Ohio. He moved to Minnesota Territory in 1855. He served in the House from March 4, 1859 to March 3, 1869.
Windom was appointed to the Senate to fill the vacancy in the term ending March 3, 1871, caused by the death of Daniel S. Norton, and served from July 15, 1870, to January 22, 1871, when a successor (Ozora P. Stearns) was elected to fill the term.
Windom was however elected to the regualar full term that started March 4, 1871. He served from to March 7, 1881 when he was appointed as United States Secretary of the Treasury by President James Garfield and served from until he resigned from the cabinet effective November, after having again been elected Senator on, to fill the vacancy caused by his own resignation, and served to March 3, 1883. He was an unsuccessful candidate for reelection in 1882. He moved to New York City in 1883 and practiced law. He was appointed Secretary of Treasury again in the Cabinet of President Benjamin Harrison and served from March 1889 until his death in New York.