German submarine U-108 was a Type IXB U-boat of Nazi Germany's Kriegsmarine that operated during World War II.

She was laid down at DeSchiMAG AG Weser in Bremen as yard number 971 on 27 December 1938, launched on 15 July 1940 and commissioned on 22 October under Korvettenkapitän Klaus Scholtz.

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 metric horsepower (740 kW; 990 shp) for use while submerged.

She crossed the North Sea and entered the Atlantic via the gap between Iceland and the Faroe Islands, sinking Texelstroom on 22 February.

Her second foray involved the sinking of HMS Rajputana, an armed merchant cruiser, west of Reykjavík on 13 April 1941.

She went on to sink Baron Nairn west of Cape Race (eastern Newfoundland and Labrador) on the eighth; the Greek ship Dirphys 600 nautical miles (1,100 km; 690 mi) east of Newfoundland, also on 8 July; Christian Krohg on the tenth; Ellinco on the 25th; Nicholas Pateras on the same day and Toronto on 1 July.

She sank Cassequel, a neutral vessel, on 14 December 1941, 160 nmi (300 km; 180 mi) southwest of Cape St. Vincent, Portugal and Ruckinge (convoy HG 76) on the 19th, west of Lisbon as part of her fifth sortie.

The boat's sixth patrol, as part of Operation Drumbeat (Paukenschlag),[4] took her to the east coast of North America where she was again successful, sinking Ocean Venture on 8 February 1942, Tolosa on the ninth and Blink on the 12th.

The U-boat had chased Blink, which had been hit by a non-detonating torpedo, the two vessels almost collided; which was only avoided by U-108 diving underneath the merchant ship.

The boat's seventh patrol was almost as successful as her sixth, sinking Modesta on 25 April 1942, Mobiloil on the 29th (which required a total of six torpedoes and many rounds from the 20mm and 37mm guns), Afoundria on 5 May, and Abgara a day later.