German submarine U-406 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.
She was laid down on 6 September 1940 by Danziger Werft, Danzig as yard number 107, launched on 16 June 1941 and commissioned on 22 October 1941 under Oberleutnant zur See Horst Dietrichs, the ship's only commander.