List of state leaders in 842

841 state leaders – Events of 842 – 843 state leaders – State leaders by year

Asia

• China (Tang Dynasty) - Wuzong, Emperor of Tang China (840–846)
• Gurjara - Mihira Bhoja I, Pratihara King of Gurjara (c. 836–886)
• Japan (Heian Period) - Emperor Nimmyō, emperor of Japan (833–850)
• Korea (North South States Period)
  • Balhae - Dae Ijin, King of Balhae (830–857)
  • Silla - Munseong, King of Silla (839–857)

Europe

• Bulgaria - Presian, Khan of the Bulgars (836–852)
• Byzantine Empire -
  1. Theophilos (829–842)
  2. Michael III (842–867)
• Caucasus
  • Principate of Iberia - Bagrat I Kuropalates (830–876)
  • Principality of Kakheti - Samuel, Prince of Kakheti (839–861)
• Kingdom of Denmark - Horik I (813–854)
• England (Heptarchy) -
  • Kingdom of East Anglia - Æthelweard (839–854)
  • Mercia - Beorhtwulf, King of Mercia (840–852)
  • Northumbria - Æthelred II, King of Northumbria (841–844)
  • Wessex - Æthelwulf, King of Wessex (839–856) and King of Kent (839–856)
• Frankish Empire - Lothair I, King of Italy and Holy Roman Emperor (817–855)
  • County of Angoulême - Turpion (839–863)
  • Aquitaine -
  • Pepin II of Aquitaine, King of Aquitaine (838–851/852)
  • Charles the Bald, King of Aquitaine (838–855)
    • Gascony - Sans II Sancion of Gascony, Count of Gascony (836–864)
    • Toulouse - Bernard of Septimania, Count of Toulouse (835–842)
  • County of Barcelona - Bernard of Septimania (835–844)
  • Bavaria - Louis the German, King of Bavaria (817–843)
  • Littoral Croatia - Mislav of Croatia, Duke of Littoral Croatia (835–845)
  • County of Maine - Gauzbert (840–853)
  • County of Nantes - Renaud (841–843)
  • Poitiers - Bernard II, Count of Poitiers (840–844)
  • County of Urgell - Sunifred I (834–848)
• Ireland - Niall Caille, High King of Ireland (833–846)
  • Ailech - Niall Caille, King of Ailech (823–846)
  • Connacht - Fergus mac Fothaid, King of Connacht (840–843)
  • Uí Maine - Cathal mac Ailell, King of Uí Maine (834–844)
  • Leinster - Ruarc mac Brain, King of Leinster (838–847)
  • Kingdom of Mide - Máel Ruanaid mac Donnchada Midi (833–843)
  • Munster - Feidlimid mac Cremthanin, King of Munster (820–847)
  • Kingdom of Osraige - Cerball mac Dúnlainge (842–888)
  • Ulaid - Matudán mac Muiredaig, King of Ulaid (839–857)
• Italy - Lothair I, King of Italy and Holy Roman Emperor (818–855)
  • Principality of Benevento - Radelchis I (839–851)
  • Duchy of Gaeta - Constantine, Hypatus of Gaeta (839–866)
  • Duchy of Naples - Sergius I (840–864)
  • Papal States - Pope Gregory IV (827–844)
  • Principality of Salerno - Siconulf (839–851)
  • Duchy of Spoleto - Guy I (842–860)
  • Venice - Pietro Tradonico, Doge of Venice (836–864)
• Great Moravia - Mojmír I, Prince of Great Moravia (831–846)
• Scotland
  • Picts -
    1. Uurad, King of the Picts (839–842)
    2. Bridei VI, King of the Picts (842)
    3. Ciniod II, King of the Picts (842)
    4. Bridei VII, King of the Picts (842–845)
• Serbia - Vlastimir, Zupan of Serbia (835–850)
• Spain -
  • County of Aragon - Galindo Garcés (833–844)
  • Kingdom of Asturias -
    1. Alfonso II (791–842)
    2. Nepocian (842)
    3. Ramiro I (842–850)
  • Caliphate of Córdoba - Abd-ar-rahman II (822–852)
  • Kingdom of Pamplona - Iñigo Arista (824–851/852)
• Wales -
  • Kingdom of Gwynedd - Merfyn Frych (825–844)
  • Kingdom of Powys - Cyngen ap Cadell (808–855)