|Millennium:||1st millennium BC|
|83 BC by topic|
|Gregorian calendar||83 BC|
|Ab urbe condita||671|
|Ancient Egypt era||XXXIII dynasty, 241|
|- Pharaoh||Ptolemy IX Lathyros, 6|
|Ancient Greek era||174th Olympiad, year 2|
|Balinese saka calendar||N/A|
|Chinese calendar||丁酉年 (Fire Rooster)|
2614 or 2554
— to —
戊戌年 (Earth Dog)
2615 or 2555
|Coptic calendar||−366 – −365|
|Ethiopian calendar||−90 – −89|
|- Vikram Samvat||−26 – −25|
|- Shaka Samvat||N/A|
|- Kali Yuga||3018–3019|
|Iranian calendar||704 BP – 703 BP|
|Islamic calendar||726 BH – 725 BH|
|Minguo calendar||1994 before ROC|
|Seleucid era||229/230 AG|
|Thai solar calendar||460–461|
44 or −337 or −1109
— to —
45 or −336 or −1108
Year 83 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Asiaticus and Norbanus (or, less frequently, year 671 Ab urbe condita). The denomination 83 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.
- Spring – Lucius Cornelius Sulla returns to Italy from his campaigns in Greece and lands with his legions unopposed at Brundisium. He defeats the popular forces of Gaius Norbanus in the Battle of Mount Tifata.
- Gnaeus Pompeius, age 22, raises on his own initiative a private army of three legions from his fathers veterans and clientelae in Picenum.
- Lucius Licinius Murena, the Roman governor of Asia, clashes with the Pontic forces of Mithridates VI, starting the Second Mithridatic War.
- A fire breaks out which burns down the Temple of Jupiter (Jupiter Capitolinus) and destroys the collection of Sibylline Books.
- Mark Antony, Roman politician (who later married Cleopatra) (approximate date) (d. 30 BC)
- Julia, daughter of Julius Caesar and Cornelia (approximate date) (d. 54 BC)
- Fulvia, Roman matron and wife of Mark Antony (approximate date)
- Philip I Philadelphus, Seleucid king (approximate date)