U-73 may refer to one of the following German submarines:
- SM U-73, a Type UE I submarine launched in 1915 and that served in World War I until scuttled on 30 October 1918
- During World War I, Germany also had these submarines with similar names:
- SM UB-73, a Type UB III submarine launched in 1917 and surrendered on 21 November 1918; broken up at Brest, France, in July 1921
- SM UC-73, a Type UC II submarine launched in 1916 and surrendered on 6 January 1919; broken up at Brighton Ferry in 1919–20
- During World War I, Germany also had these submarines with similar names:
- German submarine U-73, a Type VIIB submarine that served in World War II until sunk on 16 December 1943
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.