German submarine U-77

U-77 may refer to one of the following German submarines:


 * SMU U-77, a Type UE I submarine launched in 1916 and that served in World War I until sunk 7 July 1916
 * During World War I, Germany also had these submarines with similar names:
 * SMU UB-77, a Type UB III submarine launched in 1917 and surrendered on 16 January 1919; broken up at Swansea in 1922
 * SMU UC-77, a Type UC II submarine launched in 1916 and sunk on 14 July 1918
 * GS U-77 (1940), a Type VIIC submarine that served in World War II until sunk on 28 March 1943