List of state leaders in 818

Asia

*Bohai/Balhae -
*#Da Mingzhong/Dae Myeong-chung, King of Bohai/Balhae (817?-818?)
*#Da Renxiu/Dae In-su, King of Bohai/Balhae (818?-830)
*China (Tang Dynasty) - Xianzong, Emperor of Tang China (806-820)
*Gurjara - Nagabhata II, Pratihara King of Gurjara (805-833)
*Japan (Heian Period) - Emperor Saga, Emperor of Japan (809-823)
*Silla - Heondeok, King of Silla (809-826)

Europe

*Asturias - Alfonso II, King of Asturias (791-842)
*Bulgaria - Omurtag, Khan of Bulgaria (814-831)
*England (Heptarchy) - Cenwulf of Mercia, Bretwalda (796-821)
**East Anglia - Coenwulf, King of East Anglia (799–821)
*Mercia - Cenwulf, King of Mercia (796-821) and East Anglia (c.799-821) and King of Kent (807-821)
**Northumbria - Eanred, King of Northumbria (810–841)
**Essex - Sigered, King of Essex (798–825)
**Wessex - Egbert of Wessex, King of Wessex and Bretwalda (802–839)
*Frankish Empire - Louis the Pious, Holy Roman Emperor (816-840)
*Ireland - Conchobar mac Donnchada, High King of Ireland (818–831)
*Picts - Caustantín, King of the Picts (789–820)
*Strathclyde - Arthgal f Dyfnwal, King of Strathclyde (816–872)
*Venice - Agnello Participazio, Doge of Venice (811-827)
*Wales - Hywel "Farf-Fehinog" ab Caradog, King of Gwynedd (814–825)

Middle East

*Abbasid Caliphate - Al-Ma'mun, Caliph (813-833)
*Byzantine Empire - Leo V The Armenian, Byzantine Emperor (813-820)