According to her Wikipedia article, she was the daughter of Isabel of Portugal and sister of Holy Roman Empress Maria of Austria, briefly married to João Manuel of Portugal (who died of illness), King Sebastian of Portugal’s mother, and regent for Felipe II of Spain. She founded the Convent of Our Lady of Consolation (Nuestra Señora de la Consolación) in 1557. She also acted on behalf of the Jesuits.

1552-1553 Juana de Habsburgo in gold-embroidered black dress by follower of Anthonis Mor (Royal Collection)

Full length portrait of Juana de Habsburgo in a gold-embroidered black dress (embajada española - Buenos Aires, Argentina)

ca. 1557 Juana of Austria, Princess of Portugal by Alonso Sánchez Coello (Museo de Bellas Artes de Bilbao - Bilbao, Vizcaya Spain)
