Epirus was an ancient Greek kingdom, and later republic, located in the geographical region of Epirus, in parts of north-western Greece and southern Albania. Home to the ancient Epirotes, the state was bordered by the Aetolian League to the south, Ancient Thessaly and Ancient Macedonia to the east, and Illyrian tribes to the north. The Greek king Pyrrhus is known to have made Epirus a powerful state in the Greek realm that was comparable to the likes of Ancient Macedonia and Ancient Rome. Pyrrhus' armies also attempted an assault against the state of Ancient Rome during their unsuccessful campaign in what is now modern-day Italy.

Epirus is a geographical and historical region in southeastern Europe, now shared between Greece and Albania. It lies between the Pindus Mountains and the Ionian Sea, stretching from the Bay of Vlorë and the Acroceraunian Mountains in the north to the Ambracian Gulf and the ruined Roman city of Nicopolis in the south. It is currently divided between the region of Epirus in northwestern Greece and the counties of Gjirokastër and Vlorë in southern Albania. The largest city in Epirus is Ioannina, seat of the Greek region of Epirus, with Gjirokastër the largest city in the Albanian part of Epirus.