|Centuries:||7th century – 8th century – 9th century|
|Decades:||750s 760s 770s – 780s – 790s 800s 810s|
|Years:||780 781 782 – 783 – 784 785 786|
|783 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1536|
|Chinese calendar||壬戌年 (Water Dog)
3479 or 3419
— to —
癸亥年 (Water Pig)
3480 or 3420
|- Vikram Samvat||839–840|
|- Shaka Samvat||705–706|
|- Kali Yuga||3884–3885|
|Japanese calendar||Enryaku 2
|Minguo calendar||1129 before ROC
|Seleucid era||1094/1095 AG|
|Thai solar calendar||1325–1326|
Year 783 (DCCLXXXIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. The denomination 783 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.
- Arab–Byzantine War: A Byzantine expeditionary force under Staurakios, chief minister (logothete), begins a campaign against the communities (Sclaviniae) of Greece. Setting out from Constantinople, the imperial army follows the Thracian coast into Macedonia, and then south into Thessaly, Central Greece and the Peloponnese. Staurakios restores a measure Byzantine authority over these areas, and collects booty and tribute from the locals.
- Mauregatus of Asturias, illegitimate son of the late king Alfonso I, usurps the throne after the death of his brother-in-law Silo. However, the nobility has elected Alfonso II at Adosinda's (wife of Silo) insistence, but Mauregatus assembles a large army of supporters and forces Alfonso to flee to Álava (modern Spain). Adosinda is put in the monastery of San Juan de Pravia, where she lives out the rest of her life.
- April 30 – Hildegard, wife of king Charlemagne, dies in childbirth after her ninth confinement in less than 12 years of marriage. His mother, Bertrada of Laon, dies in the summer and is buried with great ceremony beside her husband Pepin the Short in the Abbey of St. Denis (modern-day Paris).
- October – Charlemagne marries Fastrada, the 18-year-old daughter of an Frankish count named Rudolph, and makes her his queen at Worms. The probable reason behind the marriage is to solidify a Frankish alliance east of the Rhine against the Saxons in Lower Saxony (modern Germany).
- Winter – Saxon Wars: Charlemagne defeats the Saxon 'rebels' in a three-day battle next to the Hase River and perhaps overruns fortifications on the Wittekindsberg before ravaging southern Saxony. A Frisian uprising against Carolingian rule is supported by duke Widukind.
- July 12 – Bertrada of Laon, wife of Pepin the Short
- Cynewulf, bishop of Lindisfarne (approximate date)
- Fujiwara no Uona, Japanese minister (b. 721)
- Han Gan, Chinese painter of the Tang Dynasty
- April 30 – Hildegard, wife of Charlemagne (b. 758)
- Isa ibn Musa, Muslim governor (or 784)
- Silo, king of Asturias (Spain)
- David Nicolle (2014). The Conquest of Saxony AD 782–785, p. 20. ISBN 978-1-78200-825-5