The German submarine U-109 was a Type IXB U-boat of the Nazi German Kriegsmarine that operated during World War II. She conducted nine war-patrols, sinking 12 ships and damaging one. All but one of these successes were during the six patrols she carried out under the command of the U-boat ace, Heinrich Bleichrodt. On 4 May 1943, she was sunk with all hands by a B-24 Liberator, operated by 86 Squadron RAF.