|Millennium:||1st millennium BC|
|Centuries:||4th century BC – 3rd century BC – 2nd century BC|
|Decades:||290s BC 280s BC 270s BC – 260s BC – 250s BC 240s BC 230s BC|
|Years:||268 BC 267 BC 266 BC – 265 BC – 264 BC 263 BC 262 BC|
|265 BC by topic|
|Gregorian calendar||265 BC|
|Ab urbe condita||489|
|Bahá'í calendar||−2108 – −2107|
|English Regnal year||N/A|
|Chinese calendar||乙未年 (Wood Goat)
2432 or 2372
— to —
丙申年 (Fire Monkey)
2433 or 2373
|Coptic calendar||−548 – −547|
|Ethiopian calendar||−272 – −271|
|- Vikram Samvat||−208 – −207|
|- Shaka Samvat||N/A|
|- Kali Yuga||2837–2838|
|Igbo calendar||−1264 – −1263|
|Iranian calendar||886 BP – 885 BP|
|Islamic calendar||913 BH – 912 BH|
|Minguo calendar||2176 before ROC
|Thai solar calendar||279|
|Wikimedia Commons has media related to 265 BC.|
Year 265 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Gurges and Vitulus (or, less frequently, year 489 Ab urbe condita). The denomination 265 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.
- Although the Egyptian fleet blockades the Saronic Gulf, the Macedonian King Antigonus II defeats the Spartans and kills the King of Sparta, Areus I near Corinth, after which he besieges Athens.
- Acrotatus II succeeds his father Areus I as king of Sparta.
- Hiero II threatens to renew his attack on the Mamertines. They appeal to Carthage and receive the support of a Carthaginian garrison. The Mamertines also appeal to the Romans who are also willing to help.
- The Battle of Messana (265-264 BCE) takes place as the first military clash between the Roman Republic and Carthage.
- The Etruscan city of Volsinii was brought under Roman control.
Arts & sciences
- The Archimedes screw for raising water is devised by the Greek mathematician Archimedes, who is studying at Alexandria.