U-133 may refer to one of the following German submarines:
- SM U-133, a Type U 127 submarine laid down during the First World War but unfinished at the end of the war; broken up incomplete 1919–20
- During the First World War, Germany also had this submarine with a similar name:
- SM UB-133, a Type UB III submarine launched in 1918
- During the First World War, Germany also had this submarine with a similar name:
- German submarine U-133 (1941), a Type VIIC submarine that served in the Second World War until sunk 14 March 1942
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.