German submarine U-55 was a Type VIIB U-boat of the Nazi German Kriegsmarine during World War II. She was ordered on 16 July 1937 and laid down on 2 November 1938 at Krupp Germaniawerft in Kiel as Werk 590. Launched on 19 October 1939, she went into service on 21 November 1939 under the command of Kapitänleutnant (Kptlt.) Werner Heidel.