William Joseph Lynch (June 6, 1908 – August 9, 1976) was a United States federal judge.
Lynch was born in Chicago, Illinois, on June 6, 1976. He received an LL.B. from Loyola University Chicago School of Law in 1931 and entered private practice in Chicago. He was an Assistant State's Attorney from 1933 to 1938, when he returned to private practice. During World War II, he served in the United States Navy from 1942 to 1946, when he once again returned to private practice. He was a member of the Illinois Senate from 1950 to 1957. He was a Minority Leader, 1953–1957.
Lynch was nominated by President Lyndon B. Johnson on January 19, 1966, to a seat vacated by Michael L. Igoe on the United States District Court for the Northern District of Illinois. He was confirmed on March 4, 1966, and received his commission on March 7, 1966. Lynch remained on the court until his death on August 9, 1976, in Chicago, Illinois.