- king of Germany 1152–90; king of Italy 1152–90: emperor of the Holy Roman Empire 1152–90.
- king of Sicily 1198–1212: as Frederick II, king of Germany and emperor of the Holy Roman Empire 1215–50.
- king of Prussia 1701–13 (son of Frederick William the Great Elector).
- See Frederick Barbarossa
- 1657–1713, first king of Prussia (1701–13); son of Frederick William
