|Millennium:||1st millennium BC|
|Gregorian calendar||12 BC|
|Ab urbe condita||742|
|Ancient Greek era||192nd Olympiad (victor)¹|
|Balinese saka calendar||N/A|
|Chinese calendar||戊申年 (Earth Monkey)|
2685 or 2625
— to —
己酉年 (Earth Rooster)
2686 or 2626
|Coptic calendar||−295 – −294|
|Ethiopian calendar||−19 – −18|
|- Vikram Samvat||45–46|
|- Shaka Samvat||N/A|
|- Kali Yuga||3089–3090|
|Iranian calendar||633 BP – 632 BP|
|Islamic calendar||652 BH – 651 BH|
|Julian calendar||12 BC|
|Minguo calendar||1923 before ROC|
|Seleucid era||300/301 AG|
|Thai solar calendar||531–532|
115 or −266 or −1038
— to —
116 or −265 or −1037
Year 12 BC was either a common year starting on Saturday, Sunday or Monday or a leap year starting on Sunday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a common year starting on Friday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Messalla and Quirinius (or, less frequently, year 742 Ab urbe condita). The denomination 12 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.
- Marcus Valerius Messalla Appianus and Publius Sulpicius Quirinius are Roman Consuls.
- Tiberius Claudius Nero summoned to Pannonia due to severe revolt by the Delmataeians.
- Roman armies based at Xanten, Cologne and Mainz campaign beyond the Rhine.
- First official mention of Argentoratum, the city known in modern times as Strasbourg.
- Emperor Augustus is given the title Pontifex Maximus.
- Approximate date – Pyramid of Cestius erected in Rome.
- King Azes II dies. The rule of the Indo-Scythians crumbles as the Kushans, one of the five tribes of the Yuezhi who lives in Bactria expand into India to create a Kushan Empire.
- Comet Halley makes an appearance.
- Marcus Valerius Messalla Barbatus, member of the Roman Senate (d. c. AD 20 or 21)
- Marcus Vipsanius Agrippa Postumus, son of Julia the Elder and grandson of Augustus (d. AD 14)
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