Year 676 (DCLXXVI) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. The denomination 676 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||1429|
|Balinese saka calendar||597–598|
|Chinese calendar||乙亥年 (Wood Pig)|
3372 or 3312
— to —
丙子年 (Fire Rat)
3373 or 3313
|- Vikram Samvat||732–733|
|- Shaka Samvat||597–598|
|- Kali Yuga||3776–3777|
|Minguo calendar||1236 before ROC|
|Seleucid era||987/988 AG|
|Thai solar calendar||1218–1219|
802 or 421 or −351
— to —
803 or 422 or −350
- Summer – Siege of Constantinople: Caliph Muawiyah I sends his son Yazid with Muslim reinforcements to Constantinople. At the same time, the Byzantines have to face a Slavic attack on Thessaloniki and Lombard attacks in Italy.
- Dagobert II, son of the late king Sigibert III, becomes (partly with the help of bishop Wilfrid) the new ruler of Austrasia, after his predecessor Clovis III is murdered.
- King Æthelred of Mercia invades Kent, in an attempt to enforce overlordship and diminish Kentish influence in Surrey and London. His armies destroy the Diocese of Rochester  (seat of the bishops in West Kent), and ravage the surrounding countryside.
- King Æscwine of Wessex dies after a 2-year reign, and is succeeded by Centwine, son of the late king Cynegils. He reasserts the power of his Anglo-Saxon kingdom over the Welsh.
- Emperor Tenmu of Japan promulgates a decree about taxes from fiefs, and the employment of persons for the service from the outer provinces. Men of distinguished ability are allowed to enter the service, even though they are of the common people, regardless of their ranks.
- The broad-based peninsular effort under Silla's leadership, to prevent Chinese domination of Korea, succeeds in forcing Chinese troops to withdraw into Manchuria, in northeast China.
- Aldhelm, Anglo-Saxon scholar-poet, founds Malmesbury Abbey on the site of the hermitage of his old tutor Máel Dub.
- Æthelred of Mercia founds the monastery at Breedon on the Hill on the site of The Bulwarks, an Iron Age hill fort.
- June 17 – Pope Adeodatus II dies at Rome after a reign of 4 years. He is succeeded by Donus as the 78th pope.
- Cuthbert of Lindisfarne retires to a hermitage near Holburn, at a place now known as St. Cuthbert's Cave.
- Treadgold (1997), p. 326
- Bede, "Ecclesiastical History", chapter IV, p. 223