German submarine U-135 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down at the Vulkan-Vegesackerwerft in Bremen on 16 September 1940 as yard number 14, launched on 12 June 1941 and commissioned on 16 August with Oberleutnant zur See Friederich-Hermann Praetorius in command. U-135 began her service career in training with the 5th U-boat Flotilla, before moving on to the 7th flotilla for operations.