|Centuries:||2nd century – 3rd century – 4th century|
|Decades:||170s 180s 190s – 200s – 210s 220s 230s|
|Years:||201 202 203 – 204 – 205 206 207|
|204 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||957|
|Bahá'í calendar||−1640 – −1639|
|English Regnal year||N/A|
|Chinese calendar||癸未年 (Water Goat)
2900 or 2840
— to —
甲申年 (Wood Monkey)
2901 or 2841
|Coptic calendar||−80 – −79|
|- Vikram Samvat||260–261|
|- Shaka Samvat||126–127|
|- Kali Yuga||3305–3306|
|Igbo calendar||−796 – −795|
|Iranian calendar||418 BP – 417 BP|
|Islamic calendar||431 BH – 430 BH|
|Minguo calendar||1708 before ROC
|Thai solar calendar||747|
|Wikimedia Commons has media related to 204.|
Year 204 (CCIV) was a leap year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Cilo and Flavius (or, less frequently, year 957 Ab urbe condita). The denomination 204 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.
- Lucius Fabius Cilo and Marcus Annius Flavius Libo become Roman Consuls.
- The Daysan River floods Edessa.
- Gongsun Kang, a Chinese warlord of Liaodong, establishes the Daifang Commandery in northern Korea.
- Battle of Ye: Cao Cao lays siege to and captures the Yuan family headquarters of Ye.
- A trade recession in the Leptis Magna region (Africa) is alleviated by emperor Septimius Severus, he buys up the country's olive oil for free distribution in Rome.
- Philip the Arab, Roman Emperor (d. 249)
- Dong Jue, general of Shu Han
- Wei Zhao, Chinese scholar (d. 273)
- Gongsun Du, general of the Han Dynasty
- Shen Pei, minister under Yuan Shao
- Sun Yi, younger brother of Sun Quan (b. 184)
- Xin Ping
- Xu You, strategist under Yuan Shao