| Millennium: | 1st millennium BC |
|---|---|
| Centuries: | 2nd century BC – 1st century BC – 1st century |
| Decades: | 90s BC 80s BC 70s BC – 60s BC – 50s BC 40s BC 30s BC |
| Years: | 69 BC 68 BC 67 BC – 66 BC – 65 BC 64 BC 63 BC |
| 66 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 66 BC |
| Ab urbe condita | 688 |
| Armenian calendar | N/A |
| Bahá'í calendar | -1909 – -1908 |
| Bengali calendar | -658 |
| Berber calendar | 885 |
| Buddhist calendar | 479 |
| Burmese calendar | -703 |
| Byzantine calendar | 5443 – 5444 |
| Chinese calendar | 甲年 (2571/2631) — to —
[[Sexagenary cycle|]]年(2572/2632) |
| Coptic calendar | -349 – -348 |
| Ethiopian calendar | -73 – -72 |
| Hebrew calendar | 3695 – 3696 |
| Hindu calendars | |
| - Bikram Samwat | -9 – -8 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3036 – 3037 |
| Holocene calendar | 9935 |
| Iranian calendar | 687 BP – 686 BP |
| Islamic calendar | 708 BH – 707 BH |
| Japanese calendar | |
| Korean calendar | 2268 |
| Thai solar calendar | 478 |
Year 66 BC was a year of the pre-Julian calendar.