Joseph Winston Cox (October 19, 1875 – September 9, 1939) was an associate justice of the District Court of the United States for the District of Columbia.

Born in Bridle Creek,[1] an unincorporated community in Grayson County, Virginia, Cox received a Bachelor of Laws from George Washington University Law School in 1901.

He was in private practice in Washington, D.C. from 1901 to 1930, and was also an instructor at Georgetown Law from 1913 to 1915, a special assistant to the United States Attorney General in enforcement of anti-trust laws and matters arising in special war activities of the United States from 1914 to 1919.

He also served as a member of the District Selective Service Board from 1917 to 1918, and was a regional counsel to the United States Railroad Administration from 1919 to 1920.

His service terminated on September 9, 1939, due to his death.