Isabella of Portugal (Isabel in Portuguese and Spanish) (1428 – 15 August 1496) was Queen consort of Castile and León. She was the mother of Queen Isabella I "the Catholic".
She was born as a scion of a collateral branch of the Aviz dynasty that had ruled Portugal since 1385. Her father was John, Constable of Portugal, the youngest surviving son of John I of Portugal, and her mother was Isabella of Barcelos, a high noblewoman of some royal blood, being daughter of the first Duke of Braganza, who was an illegitimate son of John I of Portugal. Isabella of Braganza was therefore a half-niece of her husband. Isabella's father held some lordships, but was not among the forefront of the Portuguese royal house, there being a multitude of powerful dukes ahead of him.
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