Year 380 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Poplicola, Poplicola, Maluginensis, Lanatus, Peticus, Mamercinus, Fidenas, Crassus and Mugillanus (or, less frequently, year 374 Ab urbe condita). The denomination 380 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

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• Darius III, king of (Achaemenid) Persia (approximate date)
• Menaechmus, Greek mathematician and geometer (d. 320 BC)
• Pytheas, Greek explorer, who will explore northwestern Europe, including the British Isles (d. c. 310 BC) (approximate date)

• Agesipolis I, king of Sparta
• Philoxenus of Cythera, Greek dithyrambic poet (b. 435 BC)
• Hakor, king of the Twenty-ninth dynasty of Egypt
• Nefaarud II, son of Hakor and last king of the Twenty-ninth dynasty