MTB 345 was an experimental motor torpedo boat constructed in 1941, which saw limited service with the Royal Navy before being transferred to the exiled Royal Norwegian Navy on 16 March 1943. She sailed with the Royal Norwegian Navy for three months in 1943, until captured by German forces on 28 July 1943, during her second mission to the coast of occupied Norway. Two days after their capture, the crew of MTB 345 were executed by the Germans based on Hitler's Commando Order. Following their capture of MTB 345, the Germans pressed the motor torpedo boat into Kriegsmarine service, renaming her SA 12. The fate of SA 12 since December 1943 is unknown.