William Walton Morris Jr. (August 31, 1801 – December 11, 1865) was an American soldier and a career officer in the United States Army. He served as a colonel and brevet brigadier general in the Regular Army (United States), with Union Army service during the American Civil War (1861–1865). Morris served as a brigade commander primarily in charge of the defense of Fort McHenry and Baltimore Harbor. He had several brief periods in command of VIII Corps and of the Middle Department, which almost completely overlapped with each other.