U-108 may refer to one of the following German submarines:
, a Type U 93 submarine launched in 1917 that served in the First World War, and surrendered in 1918; became French submarine Léon Mignot During the First World War, Germany also had this submarine with a similar name: , a Type UB III submarine launched in 1917 and sunk in 1918 , a Type IXB submarine that served in the Second World War and was sunk in 1944