German submarine U-518 was a Type IXC U-boat of the Nazi Germany's Kriegsmarine during World War II.

The U-boat was laid down at the Deutsche Werft in Hamburg as yard number 314 on 12 June 1941, and commissioned on 25 April 1942 with Fregattenkapitän Hans-Günther Brachmann in command.

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.

[5] She left Kiel on 26 September 1942, by-passed the British Isles via the gap between Iceland and the Faeroe Islands and crossed the Atlantic.

She entered Conception Bay, Newfoundland and near Bell Island sank the Free French PLM 27 and the Canadian Rose Castle on 2 November.

A week later, on 9 November, she put a German spy named Werner von Janowski ashore at New Carlisle, Quebec.

She spent fifteen weeks on patrol which included a presence in the Gulf of Mexico, between 18 August and 1 December 1943, with no results.

By now, the Allies were besieging the Atlantic ports on the landward side; the boat departed Lorient for the last time on 15 July 1944.