HM Submarine X2 was an Italian Archimede-class submarine, originally named Galileo Galilei. She served in the Regia Marina before and during World War II, before her capture by the Royal Navy in 1940. She was stationed in the Red Sea in June 1940 as a unit of the Italian Red Sea Flotilla. During a patrol, with Capitano di Corvetta Corrado Nardi in command, on 16 June 1940, she sank the Norwegian tanker James Stove approximately 12 miles south of Aden, following which aircraft from the cruiser HMS Leander carried out a search for her without success.