Strom Thurmond was an American politician who served as a United States Senator from South Carolina from 1954 to 2003. He was the longest-serving senator in American history and was a member of the Democratic Party until 1964, when he switched to the Republican Party. He was also the Governor of South Carolina from 1947 to 1951. Thurmond was a staunch segregationist and was known for his opposition to civil rights legislation. His nickname was 'SEN. THURMOND, ' which is the answer to the crossword puzzle.