U-64 may refer to one of the following German submarines:
- SM U-64 (Germany), a Type U 63 submarine launched in 1916 and that served in the First World War until sunk on 17 June 1918
- During the First World War, Germany also had these submarines with similar names:
- SM UB-64, a Type UB III submarine launched in 1917 and surrendered on 21 November 1918; broken up at Fareham in 1921
- SM UC-64, a Type UC II submarine launched in 1917 and sunk on 20 June 1918
- During the First World War, Germany also had these submarines with similar names:
- German submarine U-64 (1939), a Type IXB submarine that served in the Second World War until sunk on 13 April 1940
This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists.