List of state leaders in 851

This is a list of heads of state, government leaders, and other rulers in the year 851.

Asia

• China (Tang dynasty) – Emperor Xuānzong (846–859)
• Pratihara Empire – Mihira Bhoja I (c. 836–886)
• Japan (Heian period) – Emperor Montoku (850–858)
• Korea (North South States Period)
  • Balhae – Dae Ijin (830–857)
  • Unified Silla – Munseong (839–857)

Europe

• First Bulgarian Empire – Presian (836–852)
• Byzantine Empire – Michael III (842–867), under the regency of Empress Theodora and Theoktistos
• Caucasus –
  • Principality of Iberia – Bagrat I Kuropalates (830–876)
  • Principality of Kakheti – Samuel (839–861)
• Kingdom of Denmark – Horik I (813–854)
• England (Heptarchy) –
  • Kingdom of East Anglia – Æthelweard (839–854)
  • Kingdom of Kent – Æthelwulf of Wessex (839–856)
  • Kingdom of Mercia – Beorhtwulf (840–852)
  • Kingdom of Northumbria – Osberht (849–862/863)
  • Kingdom of Wessex – Æthelwulf (839–856)
• East Francia – Louis the German (843–876)
  • Duchy of Saxony – Liudolf (844–866)
  • Duchy of Thuringia – Thachulf (849–873)
• Middle Francia – Lothair I (843–855)
  • Duchy of Croatia – Trpimir I (845–864)
• West Francia – Charles the Bald (843–877)
  • County of Angoulême – Turpio (839–863)
  • Kingdom of Aquitaine –
    • Pepin II of Aquitaine (838–851/852)
    • Charles the Bald (838–855)
  • County of Barcelona –
    • Aleran (850–851/852)
    • Isembard (850–852)
  • Duchy of Brittany –
    1. Nominoe (846–851)
    2. Erispoe (851–857)
  • County of Gascony – Sans II Sancion (836–864)
  • County of Maine – Gauzbert (840–853)
  • County of Nantes – Lambert II (849–851)
  • County of Poitiers – Ebroin Administrator of the County (844–854)
  • County of Toulouse – Fredelo (844–852)
  • County of Urgell – Solomon (848–869)
• Ireland – Máel Sechnaill mac Máele Ruanaid, High King of Ireland (846–862)
  • Kingdom of Ailech –
  • Kingdom of Connacht – Mugron mac Máel Cothaid (848–872)
  • Uí Maine –
  • Kingdom of Leinster
    1. Lorcán mac Cellaig (847–851)
    2. Túathal mac Máele-Brigte (851–854)
  • Kingdom of Mide – Máel Sechnaill mac Máele Ruanaid (845–862)
  • Kingdom of Munster –
    1. Ólchobar mac Cináeda (847–851)
    2. Áilgenán mac Donngaile (851–853)
  • Kingdom of Osraige – Cerball mac Dúnlainge (842–888)
  • Kingdom of Ulaid – Matudán mac Muiredaig (839–857)
• Kingdom of Italy – Lothair I (818–855)
  • Principality of Benevento –
    1. Radelchis I (839–851)
    2. Radelgar (851–854)
  • March of Friuli – Eberhard (846–863)
  • Duchy of Gaeta – Constantine, Hypatus of Gaeta (839–866)
  • Duchy of Naples – Sergius I (840–864)
  • Papal States – Pope Leo IV (847–855)
  • Principality of Salerno –
    1. Siconulf (839–851)
    2. Sico II (851–853)
  • Duchy of Spoleto – Guy I (842–860)
  • March of Tuscany – Adalbert I (847–886)
  • Republic of Venice – Pietro Tradonico, Doge of Venice (836–864)
• Great Moravia – Rastislav (846–870)
• Scotland –
  • Kingdom of the Picts – Kenneth I (848–858)
• Principality of Serbia – Mutimir, Grand Župan (850–891)
  • Strojimir, Župan of Serbia (850–856)
  • Gojnik, Župan of Rascia (850–856)
• Spain –
  • County of Aragon – Galindo Aznárez I (844–867)
  • Kingdom of Asturias – Ordoño I (850–866)
  • Emirate of Córdoba – Abd ar-Rahman II (822–852)
  • Kingdom of Pamplona –
    1. Íñigo Arista (824–851/852)
    2. García Íñiguez (851/852–882)
• Wales –
  • Kingdom of Gwynedd – Rhodri the Great (844–878)
  • Kingdom of Powys – Cyngen ap Cadell (808–855)