German submarine U-42

U-42 may refer to one of the following German submarines:

SM U-42 was ordered from Fiat-Laurenti for observation of competitive technologies; never delivered to Germany due to outbreak of war; served in the Royal Italian Navy as Balilla from 1915; sunk in July 1916 off the island of Lissa
- During the First World War, Germany also had these submarines with similar names:
  - SM UB-42, a Type UB II submarine launched in 1916 and surrendered on 16 November 1918
  - SM UC-42, a Type UC II submarine launched in 1916 and sunk on 10 September 1917
German submarine U-42 (1939), a Type IX submarine that served in the Second World War until sunk on 13 October 1939

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.