1423

1423 (MCDXXIII) was a common year starting on Friday of the Julian calendar, the 1423rd year of the Common Era (CE) and Anno Domini (AD) designations, the 423rd year of the 2nd millennium, the 23rd year of the 15th century, and the 4th year of the 1420s decade. As of the start of 1423, the Gregorian calendar was 9 days ahead of the Julian calendar, which was the dominant calendar of the time.

• April 27 – Hussite Wars: Battle of Horic – The Taborites decisively beat the Utraquists.
• July 31 – Hundred Years' War: Battle of Cravant – The French army is defeated at Cravant on the banks of the river Yonne.
• August 23 – English with Burgundian soldiers defeat the French, who were supported by the Scots, at Verneuil. The English-Burgundian alliance was strengthened by the marriage of the Duke of Bedford to Anne of Burgundy. Anne was sister of Philip the Good, Duke of Burgundy. Philip the Good had allied Burgundy with England after his father was murdered in 1419 by the French Dauphin, son of Charles VI of France.
• According to the 1421 theory, the return of Zheng He's fleets to China.

• May 30 – Georg Purbach, German astronomer and mathematician (died 1461)
• June 2 – Ferdinand I of Naples (died 1494)
• July 3 – King Louis XI of France (died 1483)
• August 24 – Thomas Rotherham, English cleric (died 1500)
• November 24 – Baron Raß von Balzers, descendant of Frederick II

• May 23 – Avignon Pope Benedict XIII (born 1328)
• October 20 – Henry Bowet, Archbishop of York
• December 15 – Michael Küchmeister von Sternberg, Grand Master of the Teutonic Knights
• date unknown – Richard Whittington, Lord Mayor of London (born 1358)