John David Dingell, Jr. (born July 8, 1926) is a Democratic United States Representative from Michigan and is currently the Dean of the U.S. House of Representatives. He is the longest serving Representative and the third longest serving Congressman ever. Since 1955, he has represented a district that was first in western Detroit but has successively moved further into that city's western suburbs, currently Michigan's 15th congressional district. Currently Dingell is the longest-serving member of the House and the second longest-serving member of Congress overall.

With the Democrats' victory in the 2006 midterm elections, Dingell again became chairman of the House Energy and Commerce Committee, a panel he previously chaired from 1981 to 1995. According to the 2008 Congress.org Power Ranking, Dingell was the fourth most powerful congressman in 2007, outranked only by fellow Democrats House Speaker Nancy Pelosi, Majority Leader Steny Hoyer, and Ways and Means Committee Chairman Charles Rangel. On November 5, 2008, representative Henry Waxman of California challenged Dingell for the chairmanship of the House Energy and Commerce Committee. Waxman defeated Dingell in a secret vote by the full Democratic Caucus on November 20, 2008 by a margin of 137 to 122. Waxman took the chairmanship of the committee starting with the 111th Congress.

Dingell was born in Colorado Springs, Colorado and is of Polish and Scots-Irish descent. He is married to Deborah Insley Dingell. His father, John D. Dingell, Sr. (1894–1955), represented Michigan's 15th district from 1933 to 1955.