Casius
Casius is:
- a river in Albania, today the Qusar (river) in Azerbaijan
- a city in Lower Egypt, near Pelusium at the Casius Mons elevation of the same name , at today's Ras Qasrun, see Kasion (Egypt)
- Titular bishopric Casius , a titular bishopric of the Roman Catholic Church, going back to the Egyptian city
- a mountain in Syria, south of Nymphaion at the mouth of the Orontes, today the Keldağ in Turkey
- Casius (Gradfeld) , MC-06 Casius, a Gradfeld on Mars