William Clark (February 1, 1891 – October 10, 1957) was a United States federal judge.
Clark was born on February 1, 1891 in Newark, New Jersey. His parents were John William Clark (1867-1928), president of the Clark Thread Company of Newark, (Clark Thread Co. later merged with J. & P. Coats to become Coats & Clark Inc.) and Margaretta Cameron Clark (1869–1941). He had two brothers, John Balfour Clark (1898-1982), who became president of the Clark Thread Company, and James Cameron Clark (1892-1976).
His maternal grandfather was United States Senator and Secretary of War during the Grant administration, J. Donald Cameron (1833–1918), who himself was the son of Simon Cameron (1799–1889), also a U.S. Senator and the Secretary of War during the Lincoln administration. His paternal grandfather was William Clark (1841–1902), the founder of the Clark Thread Company in the United States.
He studied at the Newark Academy and St. Mark's School and earned successive degrees at Harvard University, starting with a B.A. at the age of 20 in 1911, followed by an M.A. a year later, and finally an LL.B. from Harvard Law School in 1915.
Two years after graduating from Harvard Law, when the United States entered World War I, he joined the U.S. Army going to France. He stayed with the Army until 1918, rising to the rank of Captain and receiving a Silver Star for gallantry in action.