German submarine U-355 was a Type VIIC U-boat of the Nazi German Kriegsmarine during World War II. The submarine was laid down in May 1940 at the Flensburger Schiffbau-Gesellschaft yard at Flensburg, launched in July 1941, and commissioned in October under the command of Kapitänleutnant Günter La Baume. After training with the 5th U-boat Flotilla, U-355 was transferred to the 11th U-boat Flotilla, based at Bergen in Norway, for front-line service from 1 July 1942. The boat went missing on 1 April 1944 while on patrol, and was never heard from again.