1577 (MDLXXVII) was a common year starting on Tuesday of the Julian calendar, the 1577th year of the Common Era (CE) and Anno Domini (AD) designations, the 577th year of the 2ndmillennium, the 77th year of the 16thcentury, and the 8th year of the 1570s decade. As of the start of 1577, the Gregorian calendar was 10 days ahead of the Julian calendar, which was the dominant calendar of the time.

• March 17 – formation of the Cathay Company to send Martin Frobisher back to the New World for more gold
• May 28 – Publication of the Bergen Book, better known as the Solid Declaration of the Formula of Concord, one of the Lutheran confessional writings. The earlier version, known as the Torgau Book (1576), had been condensed into an Epitome; both documents are part of the 1580 Book of Concord.
• September 17 – Peace of Bergerac signed between Henry III of France and the Huguenots
• The church in San Pedro in the Atacama Desert in Chile was built.
• November – The Great Comet of 1577 passed by Earth.