Isabella I of Castile

Isabella I, also called Isabella the Catholic, was Queen of Castile and León from 1474 until her death in 1504. She was also Queen of Aragon from 1479 until her death as the wife of King Ferdinand II. Reigning together over a dynastically unified Spain, Isabella and Ferdinand are known as the Catholic Monarchs. Her reign marked the end of Reconquista and also the start of Spanish Empire and dominance of Spain over European Politics for the next century.

Isabella's marriage to Ferdinand of Aragon in 1469 created the basis of the de facto unification of Spain. With Ferdinand's help, she won the War of the Castilian Succession, securing her position as Queen of Castille. Isabella reorganized the governmental system, brought the crime rate down, and unburdened the kingdom of the debt which her half-brother King Henry IV had left behind. Her reforms and those she made with her husband had an influence that extended well beyond the borders of their united kingdoms.