|Millennium:||1st millennium BC|
|355 BC by topic|
|Gregorian calendar||355 BC|
|Ab urbe condita||399|
|Ancient Egypt era||XXX dynasty, 26|
|- Pharaoh||Nectanebo II, 6|
|Ancient Greek era||106th Olympiad, year 2|
|Balinese saka calendar||N/A|
|Chinese calendar||乙丑年 (Wood Ox)|
2343 or 2136
— to —
丙寅年 (Fire Tiger)
2344 or 2137
|Coptic calendar||−638 – −637|
|Ethiopian calendar||−362 – −361|
|- Vikram Samvat||−298 – −297|
|- Shaka Samvat||N/A|
|- Kali Yuga||2746–2747|
|Iranian calendar||976 BP – 975 BP|
|Islamic calendar||1006 BH – 1005 BH|
|Minguo calendar||2266 before ROC|
|Thai solar calendar||188–189|
−228 or −609 or −1381
— to —
−227 or −608 or −1380
Year 355 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Peticus and Poplicola (or, less frequently, year 399 Ab urbe condita). The denomination 355 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.
- King Artaxerxes III of Persia forces Athens to conclude a peace which requires the city to leave Asia Minor and to acknowledge the independence of its rebellious allies.
- King Archidamus III of Sparta supports the Phocians against Thebes in the "Sacred War".
- Chares' war party in Athens is replaced by one under Eubulus which favours peace. Eubulus restores the economic position of Athens without increasing the burden of taxation and improves the Athenian fleet while its docks and fortifications are repaired.
- Cassander, companion of Alexander the Great, successor king of Macedonia and founder of Antipatrid dynasty (approximate date) (d. c. 297 BC)