Isabella of Portugal (1503-1539) was a Portuguese princess and the daughter of King Manuel I of Portugal and Maria of Aragon. She became the Queen of Spain by marrying Charles V, the Holy Roman Emperor, in 1526. Their union strengthened the ties between Portugal and Spain, two powerful kingdoms of the time. Isabella was known for her intelligence and political acumen. She played a significant role in the governance of the Spanish Empire alongside her husband. Her marriage helped to consolidate power in Europe, and she was a key figure in the cultural and political developments of the 16th century.