Unterseeboot 429 (U-429) was a Type VIIC submarine built for the Regia Marina during World War II. Her keel was laid down on 14 September 1942 by Danziger Werft of Danzig. She was commissioned as "S-4" on 14 July 1943 under the command of an Italian captain.

When Italy surrendered on September 8, the Kriegsmarine took possession of U-429 and on 27 October 1943 gave command of her to Oberleutnant zur See Ernst-August Racky. On 16 October 1944 Oblt. Martin Kuttkat relieved Racky and commanded the boat until her loss. The submarine served as a school boat for her entire career, and never conducted a war patrol.

U-429 was bombed and sunk on 30 March 1945 near Wilhelmshaven. She did not suffer any casualties to her crew during her career.

The 2003 movie "U-Boat" features a fictional U-429, which captures the crew of a fictional USS Swordfish.

See Also: List of U-boats