|Covid-19|Byzantine–Bulgarian Wars: Krum, ruler (khan) of the Bulgarian Empire, assembles a huge army (including Slavs and Avars), for a campaign against the Byzantine Empire. He dies of a stroke, before he sets out for a major attack on Constantinople. Krum is succeeded by his son Omurtag.
January 28 – Charlemagne dies of pleurisy in Aachen, after a 13-year reign as the first Holy Roman Emperor. He is embalmed and buried in Aachen Cathedral. Charlemagne is succeeded by his son Louis the Pious, as king of the Frankish Empire.
Louis I establishes himself at the imperial court of Aachen. He appoints Benedict of Aniane as his chief advisor on religious matters, and makes him abbot of Kornelimünster Abbey, which is founded by him.
Shinsen Shōjiroku, a record of the genealogy of the ancient Japanese noble families, is completed during the reign of Emperor Saga.
Byzantine Iconoclasm: Conflict erupts between Emperor Leo V and Patriarch Nikephoros, on the subject of iconoclasm. The latter is deposed, and Nikephoros excommunicates Leo.
Bodo, Frankish deacon (approximate date)
Enchin, Japanese Buddhist monk (d. 891)
Han Yunzhong, general of the Tang Dynasty (d. 874)
Muhammad at-Taqi, Muslim ninth Ismā'īlī imam (or 813)
Wu Zong, emperor of the Tang Dynasty (d. 846)
Zhou Bao, general of the Tang Dynasty (d. 888)
January 28 – Charlemagne, king and emperor of the Franks
February 18 – Angilbert, Frankish diplomat and abbot
April 4 – Plato of Sakkoudion, Byzantine abbot
April 13 – Krum, ruler (khan) of the Bulgarian Empire
Abd-Allah ibn Numayr, Muslim narrator of hadith
Abu Nuwas, Muslim poet (b. 756)
Ailbhe of Ceann Mhara, Irish monk
Baizhang Huaihai, Chinese Zen Buddhist monk (b. 720)
Gruffydd ap Cyngen, Welsh prince (approximate date)
Li Jifu, chancellor of the Tang Dynasty (b. 758)
Meng Jiao, Chinese poet (d. 751)
Odo of Metz, Frankish architect (b. 742)
Reginfrid, Viking king of Denmark
Sugano no Mamichi, Japanese nobleman (b. 741)
Triffyn ap Rhain, king of Dyfed (approximate date)
Waldo of Reichenau, Frankish abbot and bishop
William of Gellone, Frankish nobleman (or 812)
Wu Shaoyang, general of the Tang Dynasty
Year 814 (DCCCXIV) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar.