German submarine U-637 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 17 October 1941 by Blohm & Voss, Hamburg as yard number 613, launched on 7 July 1942 and commissioned on 27 August 1942 under Kapitänleutnant Max Bernd Dieterich.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-637 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 BBC 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-637 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.
The boat's career began with training at 5th U-boat Flotilla on 27 August 1942, followed by active service on 1 June 1944 as part of the 1st Flotilla.
In three patrols she sank one warship, for a total of 39 tons.
U-637 surrendered on 9 May 1945 at Stavanger and later sunk as part of Operation Deadlight on 21 December 1945 at position .