Ferdinand I of Portugal

Dom Ferdinand I , sometimes called the Handsome or occasionally the Inconstant , was the King of Portugal and the Algarve from 1367 until his death in 1383. His death led to the 138385 crisis, also known as the Portuguese interregnum.

Ferdinand was born in Coimbra, the second but eldest surviving son of Peter I and his wife, Constanza Manuel. On the death of Peter of Castile in 1369, Ferdinand, as greatgrandson of Sancho IV by the female line, laid claim to the vacant Castilian throne. The kings of Aragon and Navarre, and later John of Gaunt, Duke of Lancaster, who had married Peter of Castiles eldest daughter, Constance, also claimed the throne.

Source: Wikipedia