Isabella, Princess of Asturias was the eldest daughter and heiress presumptive of King Ferdinand II of Aragon and Queen Isabella I of Castile. She was Queen of Portugal as the wife of King Manuel I from 30 September 1497 until her death the following year.

Ferdinand II was King of Aragon from 1479 until his death in 1516. As the husband of Queen Isabella I of Castile, he was also King of Castile from 1475 to 1504. He reigned jointly with Isabella over a dynastically unified Spain; together they are known as the Catholic Monarchs. Ferdinand is considered the de facto first king of Spain, and was described as such during his reign, even though, legally, Castile and Aragon remained two separate kingdoms until they were formally united by the Nueva Planta decrees issued between 1707 and 1716.