|Millennium:||1st millennium BC|
|Centuries:||2nd century BC – 1st century BC – 1st century|
|Decades:||110s BC 100s BC 90s BC – 80s BC – 70s BC 60s BC 50s BC|
|Years:||83 BC 82 BC 81 BC – 80 BC – 79 BC 78 BC 77 BC|
|80 BC by topic|
|Gregorian calendar||80 BC|
|Ab urbe condita||674|
|Ancient Greek era||175th Olympiad (victor)¹|
|English Regnal year||N/A|
|Chinese calendar||庚子年 (Metal Rat)
2617 or 2557
— to —
辛丑年 (Metal Ox)
2618 or 2558
|Coptic calendar||−363 – −362|
|Ethiopian calendar||−87 – −86|
|- Vikram Samvat||−23 – −22|
|- Shaka Samvat||N/A|
|- Kali Yuga||3022–3023|
|Igbo calendar||−1079 – −1078|
|Iranian calendar||701 BP – 700 BP|
|Islamic calendar||723 BH – 722 BH|
|Minguo calendar||1991 before ROC
|Thai solar calendar||464|
|Wikimedia Commons has media related to 80 BC.|
Year 80 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Sulla and Metellus (or, less frequently, year 674 Ab urbe condita). The denomination 80 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.
- Quintus Sertorius re-enter Iberia with a tiny army (2,600 men) and opens a successful campaign against the Sullan forces.
- Battle of the Baetis River: A force of Democratic exiles under Sertorius defeat the legal Roman army of Lucius Fulfidias in Hispania, starting the Sertorian War, Quintus Metellus Pius takes command on behalf of Sulla.
- Ptolemy XII Auletes succeeds Ptolemy XI Alexander II to the throne of Egypt.
- Alexandria comes under Roman jurisdiction.
- Roman artists begin to extend the space of a room visually with painted scenes of figures on a shallow stage or with a landscape or cityscape.