|Millennium:||1st millennium BC|
|180 BC by topic|
|Gregorian calendar||180 BC|
|Ab urbe condita||574|
|Ancient Egypt era||XXXIII dynasty, 144|
|- Pharaoh||Ptolemy VI Philometor, 1|
|Ancient Greek era||150th Olympiad (victor)¹|
|Balinese saka calendar||N/A|
|Chinese calendar||庚申年 (Metal Monkey)|
2517 or 2457
— to —
辛酉年 (Metal Rooster)
2518 or 2458
|Coptic calendar||−463 – −462|
|Ethiopian calendar||−187 – −186|
|- Vikram Samvat||−123 – −122|
|- Shaka Samvat||N/A|
|- Kali Yuga||2921–2922|
|Iranian calendar||801 BP – 800 BP|
|Islamic calendar||826 BH – 825 BH|
|Minguo calendar||2091 before ROC|
|Seleucid era||132/133 AG|
|Thai solar calendar||363–364|
−53 or −434 or −1206
— to —
−52 or −433 or −1205
Year 180 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Luscus and Piso/Flaccus (or, less frequently, year 574 Ab urbe condita). The denomination 180 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.
- After three years of intriguing against his younger brother Demetrius, including accusing him of coveting the succession to the Macedonian throne and being allied to Rome, Perseus persuades his father King Philip V of Macedon to have Demetrius executed.
- Rome completes its subjugation of all of Italy with the defeat of the Ligurians in a battle near modern Genoa. Rome deports 40,000 Ligurians to other areas of the Republic.
- Lucca becomes a Roman colony.
- Ptolemy VI Philometor, aged 6, rules as co-regent with his mother, Cleopatra I, who, although a daughter of a Seleucid king, does not take King Seleucus IV's side and remains on friendly terms with Rome.
- Following the death of Aristophanes of Byzantium, Aristarchus of Samothrace becomes librarian at Alexandria.
- Demetrius I starts his invasion of present-day Pakistan, following the earlier destruction of the Mauryan dynasty by general Pushyamitra Shunga.
- Apollodotus I, a general with Demetrius I of Bactria, becomes king of the western and southern parts of the Indo-Greek kingdom, from Taxila in Punjab to the areas of Sindh and possibly Gujarat. He maintains his allegiance to Demetrius I.
- September 26 — Lü Clan Disturbance
- Emperor Wen of the Han dynasty ascends to the throne.
- The state of Nanyue in Vietnam and southern China submits to the Han dynasty as a vassal.
- Apollodorus of Athens, Greek scholar and grammarian (d. c. 120 BC)
- Decimus Junius Brutus Callaicus, Roman consul (d. 113 BC)
- Viriathus, Lusitanian chieftain and general (d. 139 BC)
- Lucius Valerius Flaccus, Roman statesman, consul in 195 BC, censor in 183 BC and colleague of Cato the Elder
- Aristophanes of Byzantium, Greek scholar, critic and grammarian, particularly renowned for his work in Homeric scholarship, but also for work on other classical authors such as Pindar and Hesiod. After early studies under leading scholars in Alexandria, he has been chief librarian since about 195 BC (b. 257 BC)
- August 18 — Empress Dowager Lü, de facto ruler of the Chinese Han Dynasty and wife of Emperor Gao (b. 241 BC)
- Liu Hong, fourth emperor of the Chinese Han Dynasty (b. 190 BC)