|677 by topic|
|Ab urbe condita||1430|
|Balinese saka calendar||598–599|
|Chinese calendar||丙子年 (Fire Rat)|
3373 or 3313
— to —
丁丑年 (Fire Ox)
3374 or 3314
|- Vikram Samvat||733–734|
|- Shaka Samvat||598–599|
|- Kali Yuga||3777–3778|
|Minguo calendar||1235 before ROC|
|Seleucid era||988/989 AG|
|Thai solar calendar||1219–1220|
803 or 422 or −350
— to —
804 or 423 or −349
Year 677 (DCLXXVII) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. The denomination 677 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.
- The Onogur Bulgars are scattered by the Khazars, who then establish a great Steppe empire, centered on the Lower Volga. The Onogurs depart to the Pannonian Plain.
- Warinus, Frankish nobleman, is stoned to death near Arras, because of a feud between his brother, Leodegar (bishop of Autun), and Ebroin, the Mayor of the Palace of Neustria.
- 25–27 July: Climax of the Siege of Thessalonica: Slavic forces launch a large-scale assault on the city walls, but are repelled.
- Tang China declares the deposed Bojang of Goguryeo "King of Joseon", placing him in charge of the Liaodong area under the Protectorate General to Pacify the East.
- At Pulil, the army of Calakmul vanquishes the insurgency led by Nuun Ujol Chaak, meaning B'alaj Chan K'awiil is able to return to rule Dos Pilas, from his exile in the kingdom of Hix Witz.
- Abdallah ibn Abd al-Malik, Arab general (approximate date)
- Clovis IV, King of the Franks (d. 694)
- Muḥammad ibn ‘Alī, fifth Shi'a Imam and descendant of Prophet Muhammad (approximate date; d. 733)
- Nanyue Huairang, Chinese Zen Buddhist patriarch (d. 744)
- Constantine I, patriarch of Constantinople
- Drest VI, king of the Picts
- Vincent Madelgarius, Frankish monk
- Warinus, Frankish nobleman