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