Henry I of Portugal

Henry, dubbed the Chaste and the Cardinal-King, was King of Portugal and an inquisitor and cardinal of the Catholic Church, who ruled Portugal between 1578 and 1580. As a clergyman, he was bound to celibacy, and as such, had no children to succeed him, and thus put an end to the reigning House of Aviz. His death led to the Portuguese succession crisis of 1580 and ultimately to the 60-year Iberian Union that saw Portugal share a monarch with Habsburg Spain. The next independent monarch of Portugal would be John IV, who restored the throne after 60 years of Spanish rule. He was the only cardinal to have served as a monarch.