MV Wilhelm Gustloff was a German military transport ship which was sunk on 30 January 1945 by Soviet submarine S-13 in the Baltic Sea while evacuating German civilian refugees from East Prussia, Lithuania, Latvia, Poland and Estonia and military personnel from Gotenhafen (Gdynia) as the Red Army advanced. By one estimate, 9,400 people died, making it the largest loss of life in a single ship sinking in history.

Originally constructed as a cruise ship for the Nazi Strength Through Joy (Kraft durch Freude) organization in 1937, Wilhelm Gustloff had been requisitioned by the Kriegsmarine (German navy) in 1939. She served as a hospital ship in 1939 and 1940. She was then assigned as a floating barracks for naval personnel in Gotenhafen before being fitted with anti-aircraft guns and put into service to transport evacuees in 1945.