List of state leaders in 1255
1254 state leaders - Events of 1255 - 1256 state leaders - State leaders by year
Asia
- China (Southern Song Dynasty) - Lizong, Emperor of China (1224-1264)
- Goryeo (Korea) - King Gojong, King of Goryeo (1213-1259)
- Japan
- Monarch - Go-Fukakusa, Emperor of Japan (1246-1260)
- Shogun (Kamakura) - Prince Munetaka, Shogun of Japan (1252-1266)
- Shikken - Hojo Tokiyori, Shikken (1246-1256)
- Khmer Empire - Jayavarman VIII (1243 - 1295)
- Mongol Empire - Möngke Khan, Mongol Khan (1251-1260)
- Pagan - Narathihapate, King of Pagan (1254-1287)
- Sukhotai - Pho Khun Si Indrathit, King of Sukhothai (1249-1257)
Europe
- Achaea - William II Villehardouin, Principality of Achaea (1246-1278)
- Angouleme - Hugh II, Count of Angouleme (1249-1260)
- Bohemia - Ottokar I, King of Bohemia (1253-1278)
- Brittany - John I, Duke of Brittany (1237-1286)
- Bulgaria - Michael II Asen, King of Bulgaria (1246-1256/1257)
- Castile - Alfonso X of Castile, King of Castile and Leon (1252-1284)
- Champagne - Theobald V, Count of Champagne (1253-1270)
- Denmark - Christopher I, King of Denmark (1252-1259)
- England - Henry III, King of England (1216-1272)
- Flanders - Margaret II, Countess of Flanders (1244 - 1278)
- France - Louis IX, King of France (1226-1270)
- Gwynedd - Llywelyn the Last, Prince of Gwynedd (1246-1282)
- Holland - William II, Count of Holland (1235-1256)
- Hungary - Béla IV, King of Hungary (1235-1270)
- Navarre - Theobald II of Navarre, King of Navarre (1253-1270)
- Norway - Håkon IV, King of Norway (1217-1263)
- Poland - Boleslaus V, High Duke of Poland (1243 - 1279)
- Portugal - Alfonso III, King of Portugal (1249-1279)
- Scotland - Alexander III, King of Scotland (1249-1286)
- Sweden
- Monarch - Valdemar I, King of Sweden (1250-1275)
- Regent - Birger Jarl, regent of Sweden (1250-1266)
Middle East and North Africa
- Almohad Caliphate - Umar, Almohad Caliph (1248-1266)
- Antioch - Bohemund VI, Prince of Antioch (1252-1268)
- Armenia - Hethum I of Armenia, King of Armenia (1226-1270)
- Cyprus - Hugh II, King of Cyprus (1253-1268)
- Damascus - An-Nasir Yusuf, Ayyubid Sultan of Damascus (1250-1260)
- Egypt - Aybak, Sultan of Egypt (1254-1257)