William Milo Stone (October 14, 1827, Jefferson County, New York – July 8, 1893, Oklahoma Territory) was the sixth Governor of Iowa (1864–68).
Stone's family moved from New York to Coshocton, Ohio in 1834. He read law there and was admitted to the bar in 1851. In 1854, he moved to Knoxville, Iowa, where he opened a law practice and bought the local newspaper. In 1856, he was a delegate to the convention that formed the Republican Party, and he was an elector for 1856 Republican presidential nominee John C. Frémont. From 1857-61, he served as a state district court judge.
After the attack on Fort Sumter in 1861, Stone enlisted as a private in the Union Army. He was quickly promoted to captain, and then major, of Company B, Third Iowa Infantry. He fought and was wounded at the Battle of Liberty, but returned to fight at the Battle of Shiloh, where he was taken prisoner. Stone was paroled by Jefferson Davis and sent to Washington, D.C. to negotiate an exchange of prisoners; after initially failing to reach an agreement, he returned to Confederate captivity, was again paroled, and was released after an exchange agreement was reached. In 1862, Stone was promoted to colonel of the 22nd Iowa Infantry. He led that unit in the Vicksburg Campaign, and was again wounded at the Battle of Vicksburg.
Stone was named the Republican nominee for Governor in June 1863, and resigned from the Union Army in August. He was elected by a large margin in the general election, defeating Union general James Madison Tuttle. He was reelected in 1865. Stone was a friend of Abraham Lincoln and was present when Lincoln was assassinated at Ford's Theatre; Stone helped carry the wounded Lincoln across the street.
After leaving the governor's office in 1868, Stone served one term in the Iowa House of Representatives (1877–78), and was appointed Assistant Commissioner and then Commissioner of the U.S. General Land Office. He died of pneumonia in 1893 in Oklahoma, and is buried at Graceland Cemetery in Knoxville, Iowa.