German submarine U-36 was a Type VIIA U-boat of the Nazi German Kriegsmarine which served during World War II. She was constructed in the earliest days of the U-boat arm at Kiel in 1936, and served in the pre-war Navy in the Baltic Sea and North Sea under Kapitänleutnant (Kptlt.) Klaus Ewerth. Korvettenkapitän (KrvKpt.)Wilhelm Fröhlich took command in October 1938 and continued in the role until the boat was lost. During the war, U-36 undertook two patrols, but was sunk by a torpedo fired by HMS Salmon. She was lost with all hands.