Joanna (6 November 1479 – 12 April 1555), historically known as Joanna the Mad (Spanish: Juana la Loca), was the nominal queen of Castile from 1504 and queen of Aragon from 1516 to her death in 1555. She was the daughter of Queen Isabella I of Castile and King Ferdinand II of Aragon. Joanna was married by arrangement to the Austrian archduke Philip the Handsome on 20 October 1496.