1. ( "Frederick Barbarossa" ) 1123?-90, king of Germany 1152-90; king of Italy 1152-90: emperor of the Holy Roman Empire 1152-90.
2. 1194-1250, king of Sicily 1198-1212: as Frederick II, king of Germany and emperor of the Holy Roman Empire 1215-50.
3. 1657-1713, king of Prussia 1701-13 (son of Frederick William the Great Elector).