SM U-140 was a Type U 139 submarine that served in the Imperial German Navy in World War I. U-140 was engaged in the naval warfare and took part in the First Battle of the Atlantic.
After the end of World War I, U-140 surrendered to the United States, which used her for testing. Finally, the United States Navy destroyer sank her as a target in the Atlantic Ocean off Cape Charles, Virginia, on 22 July 1921.