Frank James Sensenbrenner Jr. (; born June 14, 1943) is an American politician who represented Wisconsin's 5th congressional district in the United States House of Representatives from 1979 to 2021 (numbered as the 9th district until 2003). He is a member of the Republican Party. He is the former chairman of the House Science Committee and the former chairman of the House Judiciary Committee; when the Republicans lost control of the House, he finished his six-year term as chairman and was not chosen as the Judiciary Committee's ranking minority member (that honor went to Lamar S. Smith of Texas). He served as the ranking Republican on the House Select Committee for Energy Independence and Global Warming from 2007 to 2011 before Republicans abolished the committee after regaining control of the House. At the time of his retirement, Sensenbrenner was the most senior member of the Wisconsin delegation and the second most senior member in the House. Sensenbrenner announced in September 2019 that he would not run for re-election in 2020.