German submarine U-90 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

She was laid down at the Flender Werke in Lübeck as yard number 294 on 1 October 1940, launched on 25 October 1941 and commissioned on 20 December with Oberleutnant zur See Hans-Jürgen Oldörp in command.

The submarine was powered by two MAN M 6 V 40/46 four-stroke, six-cylinder supercharged 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) for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged.

[1] 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).

[1] Having departed Kiel on 30 June 1942, the boat hugged the southern Norwegian coast before turning west and sailing through the gap separating the Faroe and Shetland Islands.