German submarine U-90

U-90 may refer to one of the following German submarines:


 * SMU U-90, a Type Mittel U submarine launched in 1917 and that served in the First World War until surrendered on 20 November 1918; broken up at Bo'ness in 1920–21
 * During the First World War, Germany also had these submarines with similar names:
 * SMU UB-90, a Type UB III submarine launched in 1918 and sunk on 16 October 1918
 * SMU UC-90, a Type UC III submarine launched in 1918 and surrendered on 1 December 1918; served as Japanese submarine ''O-4}}, 1920–21; broken up at [[Kure Navy Yard in 1921; used as target at submarine school at Kure, 1924–26; sold for scrap


 * GS U-90 (1941), a Type VIIC submarine that served in the Second World War until sunk on 24 July 1942