German submarine U-1235 was a Type IXC/40 U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 25 May 1943 at the Deutsche Werft yard at Hamburg, launched on 25 January 1944, and commissioned on 17 May 1944. She served with 31st U-boat Flotilla, a training unit, and with 33rd U-boat Flotilla from 1 December 1944 until 15 April 1945.

German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-1235 had a displacement of 1,144 tonnes (1,126 long tons) when at the surface and 1,257 tonnes (1,237 long tons) while submerged. The U-boat had a total length of 76.76 m (251 ft 10 in), a pressure hull length of 58.75 m (192 ft 9 in), a beam of 6.86 m (22 ft 6 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.67 m (15 ft 4 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.92 m (6 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).

The submarine had a maximum surface speed of 18.3 knots (33.9 km/h; 21.1 mph) and a maximum submerged speed of 7.3 knots (13.5 km/h; 8.4 mph). When submerged, the boat could operate for 63 nautical miles (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 13,850 nautical miles (25,650 km; 15,940 mi) at 10 knots (19 km/h; 12 mph). U-1235 was fitted with six 53.3 cm (21 in) torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm (4.13 in) SK C/32 naval gun, 180 rounds, and a 3.7 cm (1.5 in) Flak M42 as well as two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of forty-eight.

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The U-boat completed two combat patrols in early 1945, but did not sink any ships.

U-1235 was sunk on 15 April 1945 in the North Atlantic by hedgehogs from the destroyer escorts USS Stanton and USS Frost during Operation Teardrop, at position 42°54′N 30°25′W / 42.900°N 30.417°W / 42.900; -30.417.

• Helgason, Guðmundur. "The Type IXC/40 boat U-1235". German U-boats of WWII - uboat.net. Retrieved 7 December 2014.