Duke John III of Cleves was a nobleman from the House of Cleves, born in 1490. He became the Duke of Cleves in 1521 and ruled until his death in 1539. His reign was marked by political alliances and conflicts, particularly during the Reformation period in Europe. John III was known for his efforts to maintain the independence of his duchy amidst the growing power of neighboring states. He was also the brother of Anne of Cleves, who became the fourth wife of King Henry VIII of England. His legacy includes the promotion of trade and culture in the region.