|Millennium:||1st millennium BC|
|187 BC by topic|
|Gregorian calendar||187 BC|
|Ab urbe condita||567|
|Ancient Egypt era||XXXIII dynasty, 137|
|- Pharaoh||Ptolemy V Epiphanes, 17|
|Ancient Greek era||148th Olympiad, year 2|
|Balinese saka calendar||N/A|
|Chinese calendar||癸丑年 (Water Ox)|
2510 or 2450
— to —
甲寅年 (Wood Tiger)
2511 or 2451
|Coptic calendar||−470 – −469|
|Ethiopian calendar||−194 – −193|
|- Vikram Samvat||−130 – −129|
|- Shaka Samvat||N/A|
|- Kali Yuga||2914–2915|
|Iranian calendar||808 BP – 807 BP|
|Islamic calendar||833 BH – 832 BH|
|Minguo calendar||2098 before ROC|
|Seleucid era||125/126 AG|
|Thai solar calendar||356–357|
−60 or −441 or −1213
— to —
−59 or −440 or −1212
Year 187 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Lepidus and Flaminius (or, less frequently, year 567 Ab urbe condita). The denomination 187 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.
- The Seleucid king, Antiochus III, mounts a fresh expedition to the east of his kingdom in Luristan, where he is killed during an attempt to collect tribute from a temple at Elymais, Persia. He is succeeded by his son, Seleucus IV, who inherits an empire consisting of Syria (including Cilicia and Palestine), Mesopotamia, Babylonia, Media and Persia.
- Tiberius Gracchus Major is elected tribune of the plebs, in which capacity he is recorded as having saved Publius Cornelius Scipio Africanus Major from prosecution by interposing his veto. Tiberius is no friend nor political ally of Scipio's, but feels that the general's services to Rome merit his release from the threat of trial like any common criminal. Supposedly, in gratitude for this action, Scipio betrothes his youngest daughter, Cornelia, to him.
- The construction of the Via Aemilia, a trunk road in the north Italian plains, running from Ariminum (Rimini), on the Adriatic coast, to Placentia (Piacenza) on the river Padus (Po), is completed.
- Antiochus III the Great, Seleucid king of the Hellenistic Syrian Empire from 223 BC, who has rebuilt the empire in the East but failed in his attempt to challenge Roman ascendancy in Greece and Anatolia (b. c. 241 BC)