The third USS Magnet (ADG-9) was a degaussing vessel of the United States Navy, named after the magnet (the third U.S. Naval vessel to bear the name). Originally planned as a patrol craft escort (PCE-879), she was laid down on 27 May 1943 by the Albina Engine & Machine Works of Portland, Oregon; launched 30 September 1943; reclassified YDG-9 on 23 December 1943; and commissioned 10 July 1944.