Melquiades Rafael "Mel" Martinez (born October 23, 1946), né Melquíades Rafael Martínez Ruiz, is a former United States Senator from Florida and served as Chairman of the Republican Party from November 2006 until October 19, 2007, the first Latino to serve as chairman of a major party. Previously, Martínez served as the 12th Secretary of Housing and Urban Development under President George W. Bush. Martínez is a Cuban-American and Roman Catholic. He announced he was resigning as Chairman of the Republican National Committee on October 19, 2007. He is an honorary initiate of the Alpha Tau Omega Fraternity through the Eta Rho Chapter at the University of Central Florida in Orlando.

Martínez resigned his cabinet post on December 12, 2003, to run for the open U.S. Senate seat in Florida being vacated by retiring Democratic Senator Bob Graham. Martínez secured the Republican nomination and narrowly defeated the Democratic nominee, Betty Castor. His election made him the first Cuban-American to serve in the U.S. Senate. Furthermore, he and Ken Salazar (who is Mexican-American) were the first Hispanic U.S. Senators since 1977. They were joined by a third, Bob Menéndez (who is also Cuban-American) in January 2006, until Salazar resigned from the Senate on January 20, 2009, to become Secretary of the Interior. On December 2, 2008, Martinez announced he would not be running for re-election to the Senate in 2010.

On August 7, 2009, CNN and the Orlando Sentinel reported that Martinez would be resigning from his Senate seat. Later that month, Governor Crist announced that he would appoint George LeMieux as the successor to Martínez for the remaining year and a half of the Senate term.