Chester Trent Lott Sr. (born October 9, 1941) is an American lawyer, author, and politician. A former United States Senator from Mississippi, Lott served in numerous leadership positions in both the United States House of Representatives and the Senate. He entered Congress as one of the first of a wave of Republicans winning seats in Southern states that had been solidly Democratic. Later in his career, he served twice as Senate Majority Leader, and also, alternately, Senate Minority Leader. In 2003, he stepped down from the position after controversy due to his praising of senator Strom Thurmond's 1948 segregationist Dixiecrat presidential bid.

From 1968 to 1972, Lott was an administrative assistant to Representative William M. Colmer of Mississippi, who was also the chairman of the House Rules Committee. Upon Colmer's retirement, Lott won Colmer's former seat in the House of Representatives. In 1988, Lott ran successfully for the U.S. Senate to replace another retiree, John C. Stennis. After Republicans took the majority in the Senate, Lott became Senate Majority Whip in 1995 and then Senate Majority Leader in 1996, upon the resignation of presidential nominee Bob Dole of Kansas. Following GOP loses in the 2000 Senate races that resulted in a 50–50 split, Lott briefly became Senate Minority Leader, as Democrat Al Gore was still Vice President and President of the Senate at the beginning of the new term on January 3, 2001. 17 days later, Lott was restored as Senate Majority Leader after Republicans regained control of the chamber upon the inauguration of the new vice president, Dick Cheney on January 20. Lott was Senate Majority Leader until June 6, 2001, when Vermont Senator Jim Jeffords changed his party affiliation from Republican to Independent, and caucused with the Senate Democrats for the remainder of his term. Thereafter, Lott again served as Senate Minority Leader.

Following Republican gains in the 2002 midterm elections, Lott was slated to again become Majority Leader when the next Senate session began in January 2003. However, on 20 December 2002, after significant controversy following comments he made regarding Strom Thurmond's presidential candidacy, Lott resigned as Senate Minority Leader.

Though no longer in leadership, Lott remained in the Senate until resigning in 2007. Fellow Republican Roger Wicker won the 2008 special election to replace him. Lott became a lobbyist, co-founding the Breaux–Lott Leadership Group. The firm was later acquired by law and lobbying firm Patton Boggs. Lott serves as a Senior Fellow at the Bipartisan Policy Center (BPC), where he focuses on issues related to energy, national security, transportation and congressional reforms. Lott is also a co-chair of BPC's Energy Project. In June 2020 Lott was fired from the Washington law and lobbying firm Squire Patton Boggs while negotiating to join another firm. Days later on June 15, 2020, Lott joined Crossroads Strategies along with his longtime colleague John Breaux.