Diana Louise DeGette (/dɪˈɡɛt/ dih-GHET; born July 29, 1957) is an American lawyer and politician serving as the U.S. representative for Colorado's 1st congressional district since 1997. A member of the Democratic Party and a member of the Congressional Progressive Caucus, her district is based in Denver. DeGette was a Chief Deputy Whip from 2005 to 2019 and is the dean of Colorado's congressional delegation since 2007 when fellow Representative Joel Hefley retired; she served as the Colorado State Representative for the 6th district from 1993 until her election to the U.S. House.

A fourth-generation Coloradan, DeGette was born in Tachikawa, Japan, the daughter of Patricia Anne (née Rose) and Richard Louis DeGette. Her parents were American, and at the time of her birth her father was serving in the armed forces. She graduated from Colorado College, where she earned a Bachelor of Arts degree in political science and was elected to the Pi Gamma Mu international honor society in 1979. She earned her Juris Doctor degree from the New York University School of Law in 1982. She then returned to Denver and began a law practice focusing on civil rights and employment litigation.

Long active in Denver politics, DeGette was elected to the Colorado House of Representatives in 1992. She was reelected in 1994 and chosen as assistant minority leader. She authored a law that guarantees Colorado women unobstructed access to abortion clinics and other medical care facilities, also known as the Bubble Bill. The United States Supreme Court found the Bubble Bill constitutional in Hill v. Colorado, 530 U.S. 703 (2000). DeGette also authored the state Voluntary Cleanup and Redevelopment Act, a model for similar cleanup programs.^{[citation needed]}

Longtime 1st district Representative Pat Schroeder chose not to run for a 13th term in 1996, prompting DeGette to run. Her principal opponent in the primary election was former City Council member Tim Sandos, whom Denver Mayor Wellington Webb endorsed shortly before the primary. DeGette won the primary with 55% of the vote, all but assuring her of election in the heavily Democratic district (the 1st has been in Democratic hands for all but four years since 1933). Schroeder, who stayed neutral during the primary, endorsed DeGette once DeGette became the nominee. DeGette won with 57% of the vote and has been reelected 15 times since.

DeGette serves as the co-chair of both the Congressional Diabetes Caucus and Pro-Choice Caucus, and she is Vice Chair of the LGBT Equality Caucus. With the Democrats' victory in the 2006 midterm elections, DeGette briefly considered running for House Majority Whip, but bowed out in favor of Jim Clyburn of South Carolina.

DeGette sat as speaker pro tempore and presided over the debate on December 18, 2019, the day United States House of Representatives voted on the first impeachment of President Donald Trump.

DeGette received national attention in 2005, when the House of Representatives passed legislation she cosponsored to lift President George W. Bush's limits on federal funding for embryonic stem cell research. DeGette, who had been working on the measure since 2001, enlisted the support of Representative Michael N. Castle (Republican from Delaware), who became DeGette's principal Republican cosponsor of the legislation. The DeGette-Castle bill passed the Senate on July 18, 2006. President Bush vetoed the bill the next day — his first veto.

In 2007, DeGette served as the House Democrats' designated whip on the bill reauthorizing the State Children's Health Insurance Program (HR 3162). Although President Bush announced his opposition to the legislation, the House passed the bill on August 1, 2007, by a vote of 225 to 204. The Senate adopted a different version of the legislation the next day.