- John of Gaunt, son of Edward III of England and Philippa of Hainault. Brother of Edward Woodstock, Prince of Wales, known as the Black Prince.
- Known as 'of Gaunt', because he was born in the city of Ghent in Flanders.
- Married Blanche of Lancaster (1359), heiress to a vast fortune, which made him the richest man in the kingdom. They had several children, namely the future Henry IV King of England (1367-1413), and Philippa of Lancaster, future Queen of Portugal as wife of John I of Portugal.
- His second wife was Constanza of Castile (1371), daughter of Pedro the Cruel, King of Castile. Their daughter, Catalina, married Enrique III of Castile (1388), thus bringing to an end his hostilities with Enrique II and his claim to the crown of Castile on behalf of his wife.
- Had a strong influence in politics, especially through his claim to the crown of Castile, as he was married to the heir of the murdered Pedro of Castile, and also during the infancy of his nephew, the young Richard II.
- Proponent of the strategy known as the 'Chemyn de Portingale'. This involved an alliance with Portugal as a means of defeating Enrique II of Castile, thus depriving France of the naval assistance of its Castilian ally in attacking the southern shores of Engliand.
- Married Katherine Swynford later in life (1396), though they had been lovers for many years. Katherine Swynford's sister, Philippa, was married to Geoffrey Chaucer, celebrated author of the The Book of the Duchess, an apology of Blanche of Lancaster, and of The Canterbury Tales.
Duke of Lancaster
Duque de Lencastre
Allancastro
Duque d'Alancastro
Duque dAllancastro