Oscar Sydney Cox (December 3, 1905 – October 4, 1966) was an American lawyer and judge. Cox attended Massachusetts Institute of Technology and earned two degrees from Yale University Bachelor of Philosophy (1927) and a Bachelor of Laws (1929). He was associated with the well-known law firm Cadwalader, Wickersham & Taft in New York City. From 1934–1938, Cox served as Assistant Corporation Counsel for taxes. In 1938, he left New York City for a post with the United States Department of the Treasury. In 1941, Cox was appointed General Counsel of the Lend-Lease Administration and the Office for Emergency Management (1941-1943).