| Millennium: | 1st millennium BC |
|---|---|
| Centuries: | 2nd century BC – 1st century BC – 1st century |
| Decades: | 120s BC 110s BC 100s BC – 90s BC – 80s BC 70s BC 60s BC |
| Years: | 93 BC 92 BC 91 BC – 90 BC – 89 BC 88 BC 87 BC |
| 90 BC by topic | |
| Politics | |
| State leaders – Sovereign states | |
| Birth and death categories | |
| Births – Deaths | |
| Establishments and disestablishments categories | |
| Establishments – Disestablishments | |
| Gregorian calendar | 90 BC |
| Ab urbe condita | 664 |
| Armenian calendar | N/A |
| Assyrian calendar | 4661 |
| Bahá'í calendar | -1933–-1932 |
| Bengali calendar | -682 |
| Berber calendar | 861 |
| English Regnal year | N/A |
| Buddhist calendar | 455 |
| Burmese calendar | -727 |
| Byzantine calendar | 5419–5420 |
| Chinese calendar | 庚寅年 (2547/2607) — to —
辛卯年(2548/2608) |
| Coptic calendar | -373–-372 |
| Ethiopian calendar | -97–-96 |
| Hebrew calendar | 3671–3672 |
| Hindu calendars | |
| - Vikram Samvat | -33–-32 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3012–3013 |
| Holocene calendar | 9911 |
| Iranian calendar | 711 BP – 710 BP |
| Islamic calendar | 733 BH – 732 BH |
| Japanese calendar | |
| Korean calendar | 2244 |
| Minguo calendar | 2001 before ROC 民前2001年 |
| Thai solar calendar | 454 |
Year 90 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Caesar and Lupus (or, less frequently, year 664 Ab urbe condita). The denomination 90 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.