|Centuries:||4th century – 5th century – 6th century|
|Decades:||390s 400s 410s – 420s – 430s 440s 450s|
|Years:||422 423 424 – 425 – 426 427 428|
|425 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1178|
|Chinese calendar||甲子年 (Wood Rat)
3121 or 3061
— to —
乙丑年 (Wood Ox)
3122 or 3062
|- Vikram Samvat||481–482|
|- Shaka Samvat||347–348|
|- Kali Yuga||3526–3527|
|Iranian calendar||197 BP – 196 BP|
|Islamic calendar||203 BH – 202 BH|
|Minguo calendar||1487 before ROC
|Seleucid era||736/737 AG|
|Thai solar calendar||967–968|
Year 425 (CDXXV) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Theodosius and Valentinianus (or, less frequently, year 1178 Ab urbe condita). The denomination 425 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.
- Summer – Joannes, Roman usurper, is defeated at the fortified city of Ravenna and brought to Aquileia. After a humiliating parade on a donkey and the insults of the populace, he is executed.
- October 23 – Valentinian III, infant son of Galla Placidia, is installed as emperor (Augustus) of the Western Roman Empire. Real power is in the hands of his mother who becomes a regent.
- Flavius Aetius leads a force of Huns (60,000 men) into Northern Italy. He reached a compromise with Placidia in return of obtaining the rank commander-in-chief (magister militum) in Gaul.
- The Huns advance unopposed on Constantinople but are halted by a plague that decimates their hordes (see 433).
Arts and Sciences
- February 27 – The University of Constantinople is founded by emperor Theodosius II at the urging of his wife Aelia Eudocia.
- October 10 – Atticus, archbishop of Constantinople (approximate date)
- Flavius Castinus, Roman consul (approximate date)
- Flavius Gaudentius, Roman general (magister militum)
- Gamliel VI, last Nasi (head of the Sanhedrin)
- Helian Bobo, emperor of the Chinese Xiongnu state Xia (born 381)
- Joannes, Roman usurper
- Sulpicius Severus, Christian writer (approximate date)
- Yax Nuun Ayiin I 15th Ajaw of Tikal (approximate date)