Year 786 (DCCLXXXVI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. The denomination 786 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.
|Ab urbe condita||1539|
|Balinese saka calendar||707–708|
|Chinese calendar||乙丑年 (Wood Ox)|
3482 or 3422
— to —
丙寅年 (Fire Tiger)
3483 or 3423
|- Vikram Samvat||842–843|
|- Shaka Samvat||707–708|
|- Kali Yuga||3886–3887|
|Japanese calendar||Enryaku 5|
|Minguo calendar||1126 before ROC|
|Seleucid era||1097/1098 AG|
|Thai solar calendar||1328–1329|
912 or 531 or −241
— to —
913 or 532 or −240
- King Charles the Younger, son of Charlemagne and ruler of Aquitaine, visits Monte Cassino and Capua, both in Beneventan territory. Prince Arechis II, feeling threatened by the Franks, decides that he needs to stop quarrelling with the Byzantine Duchy of Naples so he can focus on the Frankish foe. Prince Arechis II therefore signs a peace agreement, or 'pactum', with the Duchy of Naples.
- Cyneheard, brother of the late king Sigeberht, ambushes and kills his rival Cynewulf of Wessex, while he is at Meretun (now called Marten) with his mistress. The Wessex nobles refuse to recognise Cyneheard as king.
- Cyneheard is executed and succeeded by Beorhtric, through the support of King Offa of Mercia. His rival claimant to the Wessex throne, a distant nephew of the late king Ine, named Egbert, is driven across the Channel.
- Egbert settles at the court of Charlemagne, and learns the arts of government during his time in Gaul. During his stay he meets Eadberht, a priest, who later becomes king of Kent.
- June 11 – Battle of Fakhkh: A Hasanid Alid uprising in Mecca is crushed by the Abbasids. One of the Alids, Idris ibn Abdallah, flees to the Maghreb in western North Africa, where he later founds the Idrisid dynasty.
- September 14 – Harun al-Rashid becomes the Abbasid caliph in Baghdad, upon the death of his brother Al-Hadi. He appoints Salim Yunisi as governor of Sindh and the Indus Valley.
- September 14 – Al-Hadi, Muslim caliph (b. 764)
- October 16 – Lullus, archbishop of Mainz
- Abo of Tiflis, Christian martyr
- Al-Rabi' ibn Yunus, Muslim minister (or 785)
- Cyneheard the Ætheling, nobleman of Wessex
- Cynewulf, king of Wessex
- Desiderius, king of the Lombards (approximate date)
- Diarmait mac Conaing, king of South Brega (Ireland)
- Sakanoue no Karitamaro, Japanese general (b. 727)
- Tipraiti mac Taidg, king of Connacht (Ireland)
- Empress Wang (Dezong) of China
- Kirby, Earliest English Kings, pp. 176-177.
In Arabic (Language) literature: There is an equation where when used; words and letters converted into numbers, thereto 786 is a conversion of words of (in Arabic) Besm Allah AlRahman AlRahim which means in English as: "In the Name of God ( ALLAH ) the Compassionate the Merciful".