Norman Mattoon Thomas (November 20, 1884 - December 19, 1968) was a leading American socialist, pacifist, and six-time presidential candidate for the Socialist Party.

The son of a Presbyterian minister, Thomas was born and raised in Marion, Ohio, and graduated from Marion High School. As a primary school age child, Thomas was a paper carrier for Warren G. Harding's Marion Daily Star. Thomas later attended and graduated from Princeton University in 1905. He then attended Union Theological Seminary, and there became a socialist. He was ordained as a Presbyterian minister in 1911, ministering in New York's East Harlem.

Thomas opposed the United States' entry into the First World War. After the war, he was one of the founders of American Civil Liberties Union. He was an unsuccessful Socialist candidate for Governor of New York in 1924. Following Eugene Debs' death in 1926, Thomas became the Socialist standard-bearer and was the party's Presidential nominee in 1928, 1932, 1936, 1940, 1944, 1948. As an articulate and engaging spokesman for democratic socialism, Thomas' influence was considerably greater than that of the typical perennial candidate. He made clear the difference between socialism and Communism, and explained the differences between the movement he represented and that of revolutionary Marxism.