Maria of Portugal, Duchess of Viseu (18 June 1521 – 10 October 1577) was an Infanta of Portugal, the only daughter of King Manuel I of Portugal and Eleanor of Austria. A noted patron of the arts and buildings, Maria's personal wealth rivaled that of her half-brother, King John III of Portugal, making her the richest woman in Portugal and one of the wealthiest princesses in Europe. Although she did not lack suitors and had several marriage proposals, Maria never married.
Maria sponsored several building projects, particularly in Carnide and the Lisbon countryside. She financed and supervised the construction of the Church of Nossa Senhora da Luz and the Hospital of Nossa Senhora dos Prazeres, which currently houses the Colégio Militar, both of which still boast large reliefs of her personal coat of arms. In Lisbon, she sponsored the construction of the Church of Santa Engrácia. The original structure she ordered to be built would be completely destroyed in 1681, which would lead to the construction of the new current church, which now serves as the National Pantheon of Portugal.