William Henry Harrison Clayton (October 13, 1840 – December 14, 1920), was an American lawyer and judge in post-Civil War Arkansas and Indian Territory Oklahoma. He served as the United States Attorney for the United States District Court for the Western District of Arkansas, as chief prosecutor in the court of "hanging judge" Isaac Parker for 14 years and as a federal judge in the Central District of the Indian Territory that became the state of Oklahoma. He served as a lieutenant in the Union Army during the U.S. Civil War and fought in some of the key battles of the war.