Carlos I of Spain, also known as Charles V, Holy Roman Emperor, was born in 1500 and ruled as King of Spain from 1516 until his abdication in 1556. He was a member of the Habsburg dynasty and inherited a vast empire that included territories in Europe, the Americas, and parts of Asia. His reign was marked by significant events, including the Spanish conquest of the Aztec Empire and the Protestant Reformation. Carlos I faced numerous challenges during his rule, including conflicts with France and the Ottoman Empire. He sought to maintain Catholicism in his realms and fought against Protestantism, leading to the Peace of Augsburg in 1555. After abdicating, he retired to the Monastery of Yuste in Spain, where he lived until his death in 1558.