William Alvah Stewart (August 16, 1903 – April 9, 1953) was a United States federal judge.
Born in Pittsburgh, Pennsylvania, Stewart received an A.B. from Amherst College in 1925 and an LL.B. from Harvard Law School in 1928. He was in private practice in Pittsburgh, Pennsylvania from 1928 to 1951. He was an Instructor, Duquesne Law School from 1930 to 1942. He was an Assistant city solicitor, Pittsburgh, Pennsylvania from 1934 to 1936. He was an Assistant county solicitor, County of Allegheny, Pennsylvania from 1936 to 1938. He was a City solicitor, Pittsburgh, Pennsylvania from 1938 to 1942. He was in the United States Army, JAG Corps from 1942 to 1946. He was a member of the Pittsburgh City Council from 1946 to 1951. He was a member of the Urban Redevelopment Authority of Pittsburgh, Pennsylvania from 1947 to 1951.
Stewart was a federal judge on the United States District Court for the Western District of Pennsylvania. Stewart was nominated by President Harry S. Truman on February 27, 1951, to a seat vacated by Nelson McVicar. He was confirmed by the United States Senate on April 24, 1951, and received his commission on April 25, 1951. Stewart served in that capacity until April 9, 1953, due to his death.