List of state leaders in 821

This is a list of heads of state, government leaders, and other rulers in the year 821.

Asia

• China (Tang dynasty) – Emperor Muzong (821–824)
• Pratihara Empire – Nagabhata II (805–833)
• Japan (Heian period) – Emperor Saga (809–823)
• Korea (North South States Period)
  • Balhae – Seon (818–830)
  • Unified Silla – Heondeok (809–826)

Europe

• First Bulgarian Empire – Omurtag, Khan of the Bulgars (814–831)
• Byzantine Empire – Michael II (820–829)
• Caucasus
  • Principality of Iberia – Ashot I Kuropalates (c. 813–830)
  • Principality of Kakheti – Grigol (786–827)
• Kingdom of Denmark – Horik I (813–854)
• England (Heptarchy) – Coenwulf of Mercia, Bretwalda (796–821)
  • Kingdom of East Anglia
    1. Coenwulf of Mercia (c. 799–821)
    2. Ceolwulf I of Mercia (c. 821–823)
  • Kingdom of Essex – Sigered, Duke of Essex (812–825)
  • Kingdom of Kent
    1. Coenwulf of Mercia (807–821)
    2. Ceolwulf I of Mercia (821–823)
  • Kingdom of Mercia
    1. Coenwulf (796–821)
    2. Ceolwulf (821–823)
  • Kingdom of Northumbria – Eanred (810–841)
  • Kingdom of Wessex – Egbert (802–839)
• Frankish Empire –
  • Louis the Pious, King of the Franks and senior Holy Roman Emperor (814–840)
  • Lothair I, King of Italy and junior Holy Roman Emperor (817–855)
  • Kingdom of Aquitaine – Pepin I of Aquitaine (817–838)
    • Auvergne – Guerin of Provence, Count of Auvergne (819–839)
    • Duchy of Gascony – Aznar Sánchez (819–836)
    • County of Toulouse – Berengar the Wise (816–835)
  • County of Barcelona – Rampon (820–825)
  • Duchy of Bavaria – Louis the German (817–843)
  • Duchy of Croatia –
    1. Borna of Croatia (c. 810–821)
    2. Vladislav of Croatia (c. 821–835)
  • County of Nantes – Lambert I (818–831)
  • County of Urgell – Aznar Galíndez I (820–834)
• Ireland – Conchobar mac Donnchada, High King of Ireland (819–833)
  • Kingdom of Ailech – Murchad mac Máele Dúin (819–823)
  • Kingdom of Connacht – Diarmait mac Tommaltaig (815–833)
  • Uí Maine –
  • Kingdom of Leinster – Muiredach mac Ruadrach (808–829)
  • Kingdom of Mide – Conchobar mac Donnchada (803–833)
  • Kingdom of Ulaid – Máel Bressail mac Ailillo (819–825)
• Kingdom of Italy – Lothair I, King of Italy and junior Holy Roman Emperor (818–855)
  • Principality of Benevento – Sico of Benevento (817–832)
  • Papal States – Pope Paschal I (817–824)
  • Republic of Venice – Agnello Participazio, Doge of Venice (811–827)
• Pannonian Croatia – Ljudevit Posavski (c. 810–823)
• Scotland –
  • Kingdom of the Picts – Óengus II (820–834)
• Spain –
  • County of Aragon – García Galíndez (820–833)
  • Kingdom of Asturias – Alfonso II (791–842)
  • Emirate of Córdoba – al-Hakam I (796–822)
• Wales –
  • Kingdom of Gwynedd – Hywel ap Rhodri Molwynog (816–825)
  • Kingdom of Powys – Cyngen ap Cadell (808–855)