1285

1285 (MCCLXXXV) was a common year starting on Monday of the Julian calendar, the 1285th year of the Common Era (CE) and Anno Domini (AD) designations, the 285th year of the 2nd millennium, the 85th year of the 13th century, and the 6th year of the 1280s decade. As of the start of 1285, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.

• January 6 – Archbishop Jakub Świnka orders all priests subject to his bishopry in Poland to deliver sermons in Polish rather than German, thus further unifying the Catholic Church in Poland and fostering a national identity.
• April 25 – Mamluk sultan Qalawun begins a siege of the Crusader fortress of Margat (in present-day Syria), a major stronghold of the Knights Hospitaller thought to be impregnable; he captures the fortress a month later.
• September 4 – Roger of Lauria defeats King Philip III of France in a naval battle off of Barcelona.
• The writ Circumspecte Agatis, issued by King Edward I of England, defines the jurisdictions of church and state in England, thereby limiting the church's judicial powers to ecclesiastical cases only.
• The Second statute of Westminster is passed in England, reforming various laws; it includes the famous clause de donis conditionalibus, considered one of the fundamental institutes of medieval law in England.
• The English romantic poem The Lay of Havelok the Dane is written (approximate date).
• Tran Hung Dao leads Vietnamese forces in victory over an invading Yuan dynasty Mongol army.