German submarine U-648 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 24 December 1941 at the Blohm & Voss yard at Hamburg, launched on 16 September 1942, and commissioned on 12 November 1942 under the command of Leutnant zur See d.R. Peter-Arthur Stahl.
Attached to 5th U-boat Flotilla based at Kiel, U-648 completed her training period on 30 April 1943 and was assigned to front-line service.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-648 had a displacement of when at the surface and while submerged. She had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-648 was fitted with five torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one SK C/35 naval gun, 220 rounds, and one twin C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
U-648 was last heard from on 22 November 1943 during her third war patrol and has been missing ever since.
U-648 was originally thought to have been sunk on November 23, 1943, at position by , and . These attacks were actually against , and , inflicting no damage.