| 266 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 266 BC |
| Ab urbe condita | 488 |
| Armenian calendar | N/A |
| Assyrian calendar | 4485 |
| Bahá'í calendar | -2109–-2108 |
| Bengali calendar | -858 |
| Berber calendar | 685 |
| English Regnal year | N/A |
| Buddhist calendar | 279 |
| Burmese calendar | -903 |
| Byzantine calendar | 5243–5244 |
| Chinese calendar | 甲午年 (2371/2431) — to —
乙未年(2372/2432) |
| Coptic calendar | -549–-548 |
| Ethiopian calendar | -273–-272 |
| Hebrew calendar | 3495–3496 |
| Hindu calendars | |
| - Vikram Samvat | -209–-208 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 2836–2837 |
| Holocene calendar | 9735 |
| Iranian calendar | 887 BP – 886 BP |
| Islamic calendar | 914 BH – 913 BH |
| Japanese calendar | |
| Korean calendar | 2068 |
| Minguo calendar | 2177 before ROC 民前2177年 |
| Thai solar calendar | 278 |
Year 266 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Pera and Pictor (or, less frequently, year 488 Ab urbe condita). The denomination 266 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.