| Infanta Beatrice | |
| Duchess of Viseu | |
| Birth Date: | 13 June 1430 |
| Death Date: | 30 September 1506 (aged 76) |
| Spouse: | Infante Fernando, Duke of Viseu |
| Issue: | |
| Father: | John, Constable of Portugal |
| Mother: | Isabella of Barcelos |
| House: | Aviz |
| Signature: | Assinatura Infanta D. Brites.svg |
Infanta Beatriz of Portugal (13 June 1430 – 30 September 1506) was a Portuguese infanta, daughter of John, Constable of Portugal (fourth son of King John I of Portugal and his wife Philippa of Lancaster), and Isabella of Barcelos, a daughter of Afonso I, Duke of Braganza.
Due to the Aviz dynasty marriage policy, Beatrice was first cousin and sister-in-law of king Afonso V of Portugal, first cousin once removed and mother-in-law of king John II of Portugal, first cousin and mother-in-law of Ferdinand II, 3rd Duke of Braganza and mother of king Manuel I of Portugal, playing an active role in politics during the consecutive reigns of Afonso V, John II and Manuel I.
Through her sister Isabella, wife of John II of Castile, she was an aunt of Isabella I of Castile, helping to settle both the Treaty of Alcáçovas and the Treaty of Terçarias de Moura between the Kingdom of Portugal and the Kingdom of 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.
Infanta Beatrice protected and encouraged Gil Vicente, a Portuguese playwright, considered as the father of the Portuguese theatre.
She founded the Religiosas da Conceição monastery, in Beja, where her husband was buried.
In 1447, Beatrice married her cousin Infante Ferdinand (Portuguese: Fernando), 2nd Duke of Viseu, son of King Edward of Portugal (her uncle). From this marriage, they had nine children: