The USS Proteus (AC-9) was a cargo ship of the United States Navy, launched on 18 December 1917. It was designed to transport supplies and equipment to support naval operations during World War I. The ship was commissioned on 24 April 1918 and served primarily in the Atlantic Ocean, playing a crucial role in logistical support. After the war, the USS Proteus continued to serve in various capacities, including as a transport vessel. It was decommissioned on 15 June 1920 and later sold for commercial use. The ship's contributions were significant in maintaining naval readiness during a critical period in history.