Isabella of Portugal was born on 24 October 1503 to King Manuel I of Portugal and Maria of Aragon. Isabella was, in part, named after her maternal grandmother, Isabella of Castile.
On 10 March 1526, she married her first cousin Charles V of Spain. They had 6 children, three of whom lived to adulthood: Philip II of Spain (born 1527), Marie of Austria (born 1528), and Joanna of Austria (born 1535). Isabella served as regent for Charles from 1529-1532 and again from 1535-1539, taking a more active role the longer she served. On 21 April 1539, while Charles was away, she gave birth to a stillborn son and contracted a fever, dying on 1 May 1539. Charles felt her death keenly and wore mourning for the rest of his life.
Isabella was originally buried in Granada near Charles’ parents, but was later moved to the Royal Monastery of San Lorenzo de El Escorial, which had been established in accordance with Charles V’s will. In addition to establishing this new religious institution, in his will Charles had asked to be buried with his wife there. Isabella’s political presence continued to be felt after her death, with her Portuguese birth giving Philip II his claim to the Portuguese throne.
Kendall W. Brown, “Isabella of Portugal (1503–1539),” ‘Women in World History: A Biographical Encyclopedia’, Encyclopedia.com, 24 November 2021. https://www.encyclopedia.com/women/encyclopedias-almanacs-transcripts-and-maps/isabella-portugal-1503-1539
“Empress Isabella of Portugal,” Museo del Prado, 2021. https://www.museodelprado.es/en/the-collection/art-work/empress-isabella-of-portugal/d4eddf35-c76c-4c11-8f2b-099f7b71d696?searchMeta=isabella%20of%20portugal
Jorge Sebastián Lozano, “Choices and Consequences. The Construction of Isabel de Portugal’s Image,” in Queenship and Political Power in Medieval and Early Modern Spain ed., Theresa Earenfight, 145-162 (Abingdon: Routledge, 2005).