- April 6 – Saint Peter of Verona is assassinated by Carino of Balsamo.
- May 15 – Pope Innocent IV issues the papal bull Ad exstirpanda , which authorizes the torture of heretics in the Medieval Inquisition. Torture quickly gains widespread usage across Catholic Europe.
- June 1 - Alfonso X is proclaimed king of Castile and León.
- December 25 – Christopher I of Denmark is crowned King of Denmark, in the Lund Cathedral.
- The Polish land of Lebus is incorporated into the German state of Brandenburg, marking the start of Brandenburg's expansion into previously Polish areas ( Neumark).
- The Swedish city of Stockholm is founded, by Birger Jarl.
- The Lithuanian city of Klaipėda ( Memel ) is founded by the Teutonic Knights.
- The town and monastery of Orval Abbey in Belgium burn to the ground; rebuilding takes 100 years.
- Thomas Aquinas travels to the University of Paris, to begin his studies there for a masters degree.
- In astronomy, work begins on the recording of the Alfonsine tables.
- The classic Japanese text Jikkunsho is completed.
- The Chinese era Chunyou ends.
- The Mongols take the westernmost province of the Song Dynasty empire.
- March 25 – Conradin, Duke of Swabia (d. 1268)
- Safi-ad-din Ardabili, Persian Sufi leader
- Eleanor de Montfort, princess of Wales (d. 1282)
- January – Bohemond V, Prince of Antioch
- January 23 – Isabella, Queen of Armenia
- February 3 – Sviatoslav III of Vladimir, Prince of Novgorod (b. 1196)
- April 6 – Saint Peter of Verona
- May 3 or May 4 – Günther von Wüllersleben, Grand Master of the Teutonic Knights
- May 30 – King Ferdinand III of Castile and Leon
- June 6 – Robert Passelewe, Bishop of Chichester
- June 9 – Otto I, Duke of Brunswick-Lüneburg
- June 29 – Abel, King of Denmark (b. 1218)
- August 1 – Giovanni da Pian del Carpine, Italian chronicler of the Mongol Empire
- November 27 – Blanche of Castile, queen of Louis VIII of France and regent of France (b. 1188)
- date unknown