William W. Knox (June 18, 1911 – August 30, 1981) was a United States federal judge.
Born in Erie, Pennsylvania, Knox received an A.B. from the University of Michigan in 1932 and a J.D. from the University of Michigan Law School in 1935. He was in private practice in Erie, Pennsylvania from 1935 to 1970.
On September 28, 1970, Knox was nominated by President Richard Nixon to a new seat on the United States District Court for the Western District of Pennsylvania created by 84 Stat. 294. He was confirmed by the United States Senate on October 8, 1970, and received his commission on October 14, 1970. Knox served in that capacity until his death, in 1981, in Erie, Pennsylvania.