German submarine U-126 was a Type IXC U-boat of the Nazi German Kriegsmarine during World War II. In six patrols, she sank 25 ships for a total of . She was laid down at the AG Weser yard in Bremen as 'werk' 989 on 1 June 1940, launched on 31 December and commissioned on 22 March 1941 under Kapitänleutnant Ernst Bauer. The submarine commenced her service with the 2nd U-boat Flotilla, an organization she would stay with, both for training and operations.