|Centuries:||1st century – 2nd century – 3rd century|
|Decades:||130s 140s 150s – 160s – 170s 180s 190s|
|Years:||163 164 165 – 166 – 167 168 169|
|166 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||919|
|Chinese calendar||乙巳年 (Wood Snake)
2862 or 2802
— to —
丙午年 (Fire Horse)
2863 or 2803
|Coptic calendar||−118 – −117|
|- Vikram Samvat||222–223|
|- Shaka Samvat||88–89|
|- Kali Yuga||3267–3268|
|Iranian calendar||456 BP – 455 BP|
|Islamic calendar||470 BH – 469 BH|
|Minguo calendar||1746 before ROC
|Seleucid era||477/478 AG|
|Thai solar calendar||708–709|
Year 166 (CLXVI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Pudens and Pollio (or, less frequently, year 919 Ab urbe condita). The denomination 166 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.
- Dacia is invaded by barbarians.
- Conflict erupts on the Danube frontier between Rome and the Germanic tribe of the Marcomanni.
- Emperor Marcus Aurelius appoints his sons as Caesars, while he and Lucius Verus travel to Germany.
- End of the war with Parthia: The Parthians leave Armenia and eastern Mesopotamia, which both become Roman protectorates.
- A plague (possibly small pox), comes from the East and spreads throughout the Roman Empire, lasting for roughly twenty years.
- The Lombards invade Pannonia (modern Hungary). They are quickly dispatched by the Roman Army.
- King Chogo of Baekje succeeds to the throne of Baekje in the Korean peninsula.
- Scholars who have denounced eunuchs are arrested, killed or banished from the capital and official life in Han Dynasty China. This was the first of the Disasters of Partisan Prohibitions, which ended in 184.
- A Roman envoy arrives by sea in Rinan commandery in southern China (central Vietnam). He travels to the Chinese capital Luoyang and is greeted by Emperor Huan of the Han Dynasty.
- Pope Soter succeeds Pope Anicetus as the twelfth pope.
- Laurence succeeds Alypius as Patriarch of Constantinople.
- Taishi Ci, first a general under Kong Rong, then Liu Yao, and later under Sun Ce and Sun Quan (d. 206)