John Mandt Nelson (October 10, 1870 – January 29, 1955) was a U.S. Representative from Wisconsin, serving nine terms in Congress between 1913 and 1933.

John Mandt Nelson was born on October 10, 1870, in Burke, Wisconsin.

[1] Nelson was elected as a Republican to the Fifty-ninth Congress to fill the vacancy caused by the death of Henry C. Adams.

He replaced Adams as the representative of Wisconsin's 2nd congressional district and was reelected for the next three congresses in the same role from September 4, 1906 till March 3, 1913.

[1] Nelson died on January 29, 1955, in Madison, Wisconsin following a long illness.