Infanta Beatriz of Portugal (1430 – 1506) was a Portuguese infanta daughter of Infante João, Lord of Reguengos (fourth son of King John I of Portugal and his wife Philippa of Lancaster) and Isabella of Braganza a daughter of Afonso, 1st Duke of Braganza.

She married her cousin, Infante Fernando, Duke of Viseu, brother of King Afonso V of Portugal. They had several children, they were: From that marriage Ferdinand had nine children:

• Infante João of Viseu (1448-1472), 3rd Duke of Viseu, 2nd Duke of Beja, 6th general of the kingdom.
• Infante Diogo of Viseu (1450-1484), 4th Duke of Viseu, 3rd Duke of Beja.
• Infante Duarte of Viseu
• Infante Dinis of Viseu
• Infante Simão of Viseu
• Infanta Leonor of Viseu (1458-1525), married John II of Portugal and became Queen of Portugal.
• Infanta Isabel of Viseu (1459-1521), married Ferdinand II, Duke of Braganza,
• Infante Manuel of Viseu, king of Portugal as Manuel I after the death of his cousin John II of Portugal.
• Infanta Catarina of Viseu

Through her sister Isabel, wife of John II of Castile, she was an aunt of Isabella of Castile.

She played an active role in politics during the reigns of Afonso V, John II and Manuel I. She helped to concretise the treaties of Alcáçovas and Terçarias de Moura with Castile, after meeting with her niece Isabella in person.
She was also predominant in the Order of Santiago, acting as tutor for her son Diogo.

es:Beatriz de Aveiro it:Beatrice d'Aviz pt:Beatriz de Portugal, Duquesa de Viseu