German submarine U-107 was a Type IXB U-boat of Nazi Germany's Kriegsmarine that operated during World War II. Between January 1941 and August 1944, she sailed on 16 active patrols at a time when a U-boat averaged a lifespan of seven to ten patrols. During that time, U-107 sank 39 Allied ships, in addition to damaging another four ships. The U-boat was launched on 2 July 1940, based at the U-boat port of Lorient, with a crew of 53 under the initial command of Günther Hessler. She was later commanded, in order, by Harald Gelhaus, Valker Simmermacher and her final commander, Karl Heinz Fritz.