Clay, William L., Jr., 1956-

William Lacy Clay Jr. (born July 27, 1956) is an American politician who served as the U.S. Representative from Missouri's 1st congressional district from 2001 to 2021. His congressional career ended after he lost in a Democratic primary to Cori Bush in 2020, after successfully defeating her in the 2018 primary.

William Lacy Clay Jr. was born in St. Louis, Missouri. His family moved to Washington, D.C., when his father, Bill Clay, was elected to Congress. In his teenage years, Clay attended public schools in Silver Spring, Maryland, and graduated from Springbrook High School in 1974. He subsequently attended the University of Maryland, College Park, earning a degree in political science and a paralegal certificate. Clay is a member of Kappa Alpha Psi fraternity. He attended Howard University School of Law, worked as an Assistant Doorkeeper of the United States House of Representatives, and worked on his father's Congressional campaigns.

Clay entered the Missouri House of Representatives in 1983, winning a special election to complete the term of Nathaniel J. "Nat" Rivers. In 1991, he was elected to the Missouri Senate. During Clay's 17 years in the Missouri legislature, he authored Missouri's Hate Crimes Law, which included gender, sexual orientation and sexual identity in the criteria for what constitutes a hate crime.

In 2000, Bill Clay announced his retirement after 32 years in Congress. The younger Clay faced a three-way Democratic primary to succeed his father, prevailing with 62% of the vote. He breezed to victory in the general election. Clay was reelected nine times, winning Democratic primaries by an average margin of 30 points. In the 2018 Democratic primary, he defeated Cori Bush, a Justice Democrat, and two other challengers with 56.7% of the vote. In the 2020 Democratic primary, Clay lost to Bush, with 45% of the vote to her 48%.