U-133 may refer to one of the following German submarines:
, 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: , a Type UB III submarine launched in 1918 , a Type VIIC submarine that served in the Second World War until sunk 14 March 1942