|Millennium:||1st millennium BC|
|281 BC by topic|
|Gregorian calendar||281 BC|
|Ab urbe condita||473|
|Ancient Egypt era||XXXIII dynasty, 43|
|- Pharaoh||Ptolemy II Philadelphus, 3|
|Ancient Greek era||124th Olympiad, year 4|
|Balinese saka calendar||N/A|
|Chinese calendar||己卯年 (Earth Rabbit)|
2416 or 2356
— to —
庚辰年 (Metal Dragon)
2417 or 2357
|Coptic calendar||−564 – −563|
|Ethiopian calendar||−288 – −287|
|- Vikram Samvat||−224 – −223|
|- Shaka Samvat||N/A|
|- Kali Yuga||2820–2821|
|Iranian calendar||902 BP – 901 BP|
|Islamic calendar||930 BH – 929 BH|
|Minguo calendar||2192 before ROC|
|Seleucid era||31/32 AG|
|Thai solar calendar||262–263|
−154 or −535 or −1307
— to —
−153 or −534 or −1306
Year 281 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Barbula and Philippus (or, less frequently, year 473 Ab urbe condita). The denomination 281 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 Battle of Corupedium in Lydia is the last battle of the Diadochi, the rival successors to Alexander the Great. It is fought between the armies of Lysimachus, King of Thrace and Macedonia, and Seleucus, ruler of Eastern Anatolia, Syria, Phoenicia, Judea, Babylonia and Iran. Seleucus kills Lysimachus during the battle.
- Following the Battle of Corupedium, Lysimachus' widow, Arsinoe, flees to Cassandrea, a city in northern Greece, where she marries her half-brother Ptolemy Keraunos. This proves to be a serious misjudgement, as Ptolemy Keraunus promptly kills two of her sons, though the third is able to escape. Arsinoe flees again, this time to Alexandria in Egypt.
- Seleucus takes over Thrace and then tries to seize Macedonia. However, he falls into a trap near Lysimachia, Thrace, set by Ptolemy Keraunos, one of the sons of Ptolemy I and Arsinoe II's half brother, who murders Seleucus and takes Macedonia for himself.
- Cineas, a Thessalian serving as chief adviser to King Pyrrhus of Epirus, after visiting Rome attempts, without success, to dissuade Pyrrhus from invading southern Italy.
- Seleucus is succeeded as ruler of the Seleucid empire by Antiochus. He is immediately beset by revolts in Syria (probably instigated by Ptolemy II of Egypt) and by independence movements in northern Anatolia.
- Although he has only a few bases in Greece, Antigonus II Gonatas lays claim to Macedonia. His claim is disputed by Antiochus I.
- Lysimachus, king of Thrace and Macedonia (b. c. 360 BC)
- Seleucus I Nicator, founder of the Seleucid Empire (b. c. 354 BC)