German submarine U-427

German submarine U-427 was a Type VIIC U boat of the German Kriegsmarine during World War II.

Built by Danziger Werft, Danzig, the U-boat was laid down on 27 July 1942, launched on 6 February 1943 and commissioned on 2 June 1943 with a crew of 53 under their Austrian commander Oberleutnant Graf Carl-Gabriel von Gudenus. It survived until the end of the war. Ironically, most U-boats achieved notoriety for the number of kills they achieved, or the total tonnage of the vessels they sank, but in the case of U-427 fame was achieved in a different way.

From its first voyage, on 20 June 1944, until the end of the war, U-427 never destroyed any of its targets. It fired torpedoes at two vessels, HMCS Haida (G63) and HMCS Iroquois (G89) on 29 April 1945, missing both, but it was for its ability to survive under harrowing circumstances that U-427 became known. In April 1945, leading up to, during, and after those two attacks, U-427 survived 678 depth charge attempts. On 2 May 1945, U-427 returned to its base at Kilbotn, Norway, where it remained for the few remaining days before Germany's surrender.

U-427 surrendered at Narvik, Norway, on 8 May 1945, and was transferred to Loch Eriboll, Scotland, on 19 May, and later to Loch Ryan as part of "Operation Deadlight" when it was sunk on 21 December 1945 at 56.06667°N, -9.58333°W.