Ferdinand the Catholic was King of Aragon (1479 1516), Sicily (1468 1516), Naples (1504 1516), Valencia, Sardinia, and Navarre, Count of Barcelona, jure uxoris King of Castile (1474-1504) and then Regent (and true ruler) of that country also from 1508 to his death, in the name of his mentally unstable daughter Joanna the Mad.