James Strom Thurmond Sr. (December 5, 1902 – June 26, 2003) was an American politician who represented South Carolina in the United States Senate from 1954 to 2003. Before his 47 years as a senator, he served as the 103rd governor of South Carolina from 1947 to 1951. Thurmond was a member of the Democratic Party until 1964, when he joined the Republican Party. He had earlier run for president in 1948 as the Dixiecrat candidate in opposition to Democrat Harry Truman, receiving over a million votes and winning four states, and endorsed Republican Dwight Eisenhower for president in the 1950s.

A staunch opponent of civil rights legislation in the 1950s and 1960s, Thurmond conducted the longest speaking filibuster ever by a lone senator, at 24 hours and 18 minutes in length, in opposition to the Civil Rights Act of 1957. In the 1960s, he voted against both the Civil Rights Act of 1964 and the Voting Rights Act of 1965. Despite his support for racial segregation, Thurmond denied the accusation that he was a racist by insisting he was a supporter of states' rights and an opponent of excessive federal authority. Thurmond switched parties ahead of the 1964 United States presidential election, saying that the Democratic Party no longer represented people like him, and endorsed Republican nominee Barry Goldwater, who also opposed the Civil Rights Act. By the 1970s, Thurmond started to moderate his stance on race, but continued to defend his prior support for segregation based on states' rights and Southern society at the time.

As a Republican, Thurmond served three times as President pro tempore of the United States Senate, and chaired the Senate Judiciary Committee from 1981 to 1987 and the Senate Armed Services Committee from 1995 to 1999. He retired in 2003 as the only member of either chamber of Congress to reach the age of 100 while still in office and the oldest-serving senator, and died less than six months later. His 47 years as a senator, a record at the time, is the fourth-longest in U.S. history behind Robert Byrd, Daniel Inouye, and Patrick Leahy. At 14 years, Thurmond was also the longest-serving Dean of the United States Senate in political history.