German submarine U-1004 was a Type VIIC/41 U-boat built for Nazi Germany's Kriegsmarine for service during World War II.

She was laid down on 15 January 1943 by Blohm & Voss, Hamburg as yard number 204, launched on 27 October 1943 and commissioned on 16 December 1943 under Oberleutnant zur See Hartmuth Schimmelpfennig.

[4] The submarine was powered by two Germaniawerft F46 supercharged six-cylinder four-stroke diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) and two BBC GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged.

When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph).

U-1004 was sunk by naval gunfire on 1 December 1945 in the North Atlantic, in position 56°10′N 10°05′W / 56.167°N 10.083°W / 56.167; -10.083, as part of Operation Deadlight.