San Demetrio London is a 1943 British World War II docudrama based on the true story of the 1940 salvage of the tanker MV San Demetrio by some of her own crew, who reboarded her after she had been set on fire by the German heavy cruiser Admiral Scheer and then abandoned, during the Battle of the Atlantic. The film was produced by Michael Balcon for Ealing Studios and directed by Charles Frend.

MV San Demetrio was a British motor tanker, notable for her service during the Second World War. She was built in 1938 for the Eagle Oil and Shipping Company. In 1940 she was damaged by enemy action in mid-Atlantic, abandoned by her crew but later re-boarded and successfully brought into harbour. She was the subject of a 1943 feature film, San Demetrio London, one of the few films that recognised the heroism of the UK Merchant Navy crews during the War.