Holy Roman emperor and King of Spain from 1516 to 1556 whose reign was mostly devoted to the Italian Wars against France. He is also known for his ardent opposition of the Protestant Reformation.
He was very physically weak and learned to speak French, Flemish, and Spanish.
He was the ruler of the Spanish Empire until his voluntary retirement in 1556 when his son Phillip II took over.
His children were Philip II of Spain, John of Austria, Margaret of Parma, Maria of Austria and Joanna of Austria.
He sustained an alliance with King Henry VIII of England.