|Centuries:||2nd century – 3rd century – 4th century|
|Decades:||250s 260s 270s – 280s – 290s 300s 310s|
|Years:||281 282 283 – 284 – 285 286 287|
|284 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1037|
|Bahá'í calendar||-1560 – -1559|
|English Regnal year||N/A|
|Chinese calendar||癸卯年 (Water Rabbit)
2980 or 2920
— to —
甲辰年 (Wood Dragon)
2981 or 2921
|- Vikram Samvat||340–341|
|- Shaka Samvat||206–207|
|- Kali Yuga||3385–3386|
|Igbo calendar||-716 – -715|
|Iranian calendar||338 BP – 337 BP|
|Islamic calendar||348 BH – 347 BH|
|Minguo calendar||1628 before ROC
|Thai solar calendar||827|
|Wikimedia Commons has media related to 284.|
Year 284 (CCLXXXIV) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Carinus and Numerianus (or, less frequently, year 1037 Ab urbe condita). The denomination 284 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 Bagaudae, a group of peasant insurgents, revolt in Gaul against the Roman Empire. The Dardani, a region located in Illyria, becomes a Roman province.
- Emperor Numerian travels through Bithynia (Asia Minor) and is murdered on his way home to Rome. After reports from his staff, he dies from an inflammation of the eyes and soldiers found his decaying corpse in a closed litter.
- November 20 – Gaius Aurelius Valerius Diocletianus, age 39, is proclaimed new emperor. He establish himself at Nicomedia (modern İzmit, Turkey) and accepts the purple imperial vestments.
- Diocletianus carries out reforms; the Roman army returns to conscription, and admits large numbers of barbarian volunteers. The old organisation of Roman legions and auxilia is abandoned.
- Sabinus Julianus, Roman usurper against Emperor Carinus, revolts in Pannonia. He invades northern Italy and declares himself emperor.
- Winter – Diocletianus advanced with his army across the Balkans.
- Patriarch Rufinus I succeeds Patriarch Dometius as Patriarch of Constantinople.
- Diophantus, Greek mathematician (approximate date)
- Marcus Aurelius Numerian, Roman Emperor
- Sun Hao, last emperor of the Kingdom of Wu (b. 242)
- Xin Xianying, daughter of Xin Pi (b. 205)