|Millennium:||1st millennium BC|
|208 BC by topic|
|Gregorian calendar||208 BC|
|Ab urbe condita||546|
|Ancient Egypt era||XXXIII dynasty, 116|
|- Pharaoh||Ptolemy IV Philopator, 14|
|Ancient Greek era||143rd Olympiad (victor)¹|
|Balinese saka calendar||N/A|
|Chinese calendar||壬辰年 (Water Dragon)|
2489 or 2429
— to —
癸巳年 (Water Snake)
2490 or 2430
|Coptic calendar||−491 – −490|
|Ethiopian calendar||−215 – −214|
|- Vikram Samvat||−151 – −150|
|- Shaka Samvat||N/A|
|- Kali Yuga||2893–2894|
|Iranian calendar||829 BP – 828 BP|
|Islamic calendar||854 BH – 853 BH|
|Minguo calendar||2119 before ROC|
|Seleucid era||104/105 AG|
|Thai solar calendar||335–336|
−81 or −462 or −1234
— to —
−80 or −461 or −1233
Year 208 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Marcellus and Crispinus (or, less frequently, year 546 Ab urbe condita). The denomination 208 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 Romans under Publius Cornelius Scipio defeat the Carthaginians under their commander Hasdrubal Barca at Baecula (Bailen) in Baetica. As a result, Hasdrubal Barca decides to cross the Pyrenees with his remaining troops into Transalpine Gaul, with the intention of joining his brother Hannibal in Italy.
- The Roman general Marcus Claudius Marcellus is killed in battle while fighting Hannibal inconclusively near Venusia, Apulia.
- Hannibal destroys a Roman force at the Battle of Petelia.
- Antiochus III advances into Bactria, which is ruled by the Greco-Bactrian king Euthydemus I, and defeated Euthydemus at the Battle of the Arius. After resisting a siege of his capital Bactra (Balkh) by the Seleucids, Euthydemus obtains an honourable peace by which Antiochus promises Euthydemus' son Demetrius the hand of one of his daughters.
- The Chinese general Zhang Han of the Qin Dynasty pacifies a peasant rebellion led by Chen Sheng and Wu Guang, and then lays siege to the rebel city of Julu.
- Liu Ruyi, Chinese prince and only son of the first Han emperor Liu Bang (d. 194 BC)
- Polybius, Greek historian, famous for his book called "The Histories" or "The Rise of the Roman Empire", covering in detail the period between 220 and 146 BC (d. 120 BC)
- Marcus Claudius Marcellus, Roman general who has captured Syracuse during the Second Punic War and has become known as "the sword of Rome" (b. 268 BC)
- Li Si, Chinese philosopher and politician (assassinated) (b. 280 BC)