John Johnston Parker was an American politician and United States circuit judge of the United States Court of Appeals for the Fourth Circuit. He was an unsuccessful nominee for associate justice of the United States Supreme Court in 1930. He was also the United States alternate judge at the Nuremberg trials of accused Nazi war criminals and later served on the United Nations' International Law Commission.

The United States Court of Appeals for the Fourth Circuit is a federal court located in Richmond, Virginia, with appellate jurisdiction over the district courts in the following districts:District of Maryland Eastern District of North Carolina Middle District of North Carolina Western District of North Carolina District of South Carolina Eastern District of Virginia Western District of Virginia Northern District of West Virginia Southern District of West Virginia