|Covid-19|Thomas the Slav, Byzantine general (tourmarchos) and usurper, continues his revolt against Emperor Michael II. He unsuccessfully besieges Constantinople, while his fleet is destroyed by Michael's Byzantine navy, using Greek fire. Khan Omurtag of Bulgaria sends a relief army, and defeats the rebels at the Battle of Kedoutos (near Heraclea).
Emperor Louis I performs public penance for causing Bernard's death, at his palace of Attigny (Ardennes), before Pope Paschal I, and the Frankish nobles (this to restore harmony and re-establish his authority).
King Ceolwulf I of Mercia invades Powys (Wales), but is beaten back by King Cyngen. He destroyes the fortress of Deganwy, and takes the kingdom later under his control (approximate date).
Al-Hakam I, Umayyad emir of Córdoba, dies after a 26-year reign. He is succeeded by his son Abd al-Rahman II, who begins a military campaign against King Alfonso II of Asturias in Al-Andalus (modern Spain).
Kim Heon-chang launches a short-lived rebellion in Silla, which gains control over much of the southern and western Korean Peninsula.
February 6 – Ukit Took becomes the last ruler (ajaw) of the Mayan city-state Copán (modern Guatemala).
Rabanus Maurus, a Frankish Benedictine monk, becomes abbot of Fulda, after the death of Eigil.
Al-Mutawakkil, Muslim caliph (d. 861)
Ibn Abi Asim, Muslim Sunni scholar (or 821)
Minamoto no Tōru, Japanese poet (d. 895)
Xuefeng Yicun, Chinese Chan master (d. 908)
June 26 – Saichō, Japanese Buddhist monk (b. 767)
Al-Hakam I, Muslim emir of Córdoba (b. 771)
Al-Waqidi, Muslim historian and biographer
Denebeorht, bishop of Worcester
Eigil of Fulda, Bavarian abbot
Gregory Pterotos, Byzantine general (strategos)
Kim Heon-chang, Silla aristocrat and rebel leader
Li Yijian, chancellor of the Tang Dynasty (b. 756)
Tahir ibn Husayn, founder of the Tahirid Dynasty
Tian Bu, general of the Tang Dynasty (b. 785)
Winiges, duke of Spoleto (Italy)
Year 822 (DCCCXXII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar.