|Centuries:||1st century BC – 1st century – 2nd century|
|Decades:||60s 70s 80s – 90s – 100s 110s 120s|
|Years:||87 88 89 – 90 – 91 92 93|
|90 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||843|
|Bahá'í calendar||−1754 – −1753|
|English Regnal year||N/A|
|Chinese calendar||己丑年 (Earth Ox)
2786 or 2726
— to —
庚寅年 (Metal Tiger)
2787 or 2727
|Coptic calendar||−194 – −193|
|- Vikram Samvat||146–147|
|- Shaka Samvat||12–13|
|- Kali Yuga||3191–3192|
|Igbo calendar||−910 – −909|
|Iranian calendar||532 BP – 531 BP|
|Islamic calendar||548 BH – 547 BH|
|Minguo calendar||1822 before ROC
|Thai solar calendar||633|
|Wikimedia Commons has media related to 90.|
Year 90 (XC) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Nerva (or, less frequently, year 843 Ab urbe condita). The denomination 90 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.
- The Romans build a small garrison in the suburbs of modern Regensburg (approximate date).
- Pliny the Younger's appointment as urban quaestor ends.
- Emperor Domitian and Nerva are Roman Consuls.
- Cologne becomes the capital of Germania Inferior.
- A humiliating peace is bought by Domitian from Decebalus of Dacia.
- Continuing his conquest of the Tarim basin, Chinese General Ban Chao defeats the Kushan led by Kanishka.
- The Roman epic poet Gaius Valerius Flaccus dies, having written works that include the Argonautica, describing the voyage of Jason and the Argonauts to retrieve the Golden Fleece from the mythical land of Colchis.
- Ptolemy, Greek mathematician, geographer, astronomer, and astrologer (d. c. 168)
- Buddhamitra, Buddhist Nun. (approximate date)
- Pedanius Dioscorides, Greek physician (approximate date) (b. c. 40 AD)
- Gaius Valerius Flaccus, Roman poet (approximate date)