Thomas Gerard Tancredo (born December 20, 1945) is an American politician from Colorado, who represented the state's sixth congressional district in the United States House of Representatives from 1999 to 2009 as a Republican. He ran for President of the United States during the 2008 election, and was the Constitution Party's unsuccessful nominee for Governor of Colorado in 2010.

Tancredo was elected to the Colorado House of Representatives in 1976 and served two terms. After working in the United States Department of Education during the Ronald Reagan and George H. W. Bush administrations, he was elected to the United States Congress, and served five terms. He decided to not seek re-election in 2008, instead running a presidential campaign, centered on the issues of illegal immigration and terrorism. He dropped out of the race in December 2007 to assist former Massachusetts Governor Mitt Romney in his campaign for the nomination.

Tancredo announced on July 26, 2010, that he planned to change parties and run for Governor of Colorado on the American Constitution Party ticket. He received 617,030 votes (36.7%), coming in second place, well ahead of the Republican Party nominee Dan Maes, who got about 11% of the vote.

Tancredo ran for governor in 2014, this time as a Republican, because of his opposition to Colorado governor John Hickenlooper's refusal to execute convicted murderer Nathan Dunlap, and because of Hickenlooper's attempts to pass gun control legislation. Tancredo competed for the Republican Party's nomination with Bob Beauprez, Steve House, Greg Brophy, Mike Kopp, and Scott Gessler. Tancredo lost the primary to Beauprez. He once again left the Republican Party in 2015, becoming an independent. Tancredo again ran as a Republican for governor in 2018, but withdrew from the race.