John Randolph Thune (born January 7, 1961) is the Republican junior U.S. Senator from the state of South Dakota.

Born and raised in South Dakota, Thune attended college at Biola University in California before returning to his home state to obtain a graduate degree at the University of South Dakota. He worked as a legislative aide to U.S. Senator James Abdnor and served in the Reagan Administration in the Small Business Administration, before winning election to the House of Representatives in 1996. After three terms in the House, he unsuccessfully challenged Democrat Tim Johnson in the U.S. Senate race in 2002, losing by a mere 524 votes (0.15%). Thune was elected to the Senate two years later, defeating the incumbent Democrat and serving Senate Minority Leader, Tom Daschle.

John Randolph Thune was born in Murdo, South Dakota to Yvonne Patricia Bodine and Harold Richard Thune. Thune's paternal grandfather was an immigrant from Norway who partnered with his brother to start Thune Hardware stores in Mitchell and Murdo, South Dakota. He was raised in the small-town of Murdo, South Dakota. An evangelical Christian, Thune graduated with a B.A. degree in Business from Biola University, an Evangelical Christian college near Los Angeles in 1983. Thune received an MBA from the University of South Dakota in 1984. He married the former Kimberley Weems of Doland, South Dakota, in 1984; both are committed Evangelical Christians. They have two daughters, Brittany and Larissa.