- (1354-1397) Son of King Pedro of Portugal and his tragic mistress Dona Inês de Castro.
- Witnessed King Fernando swearing his pledge to the Treaty of Alcoutim (May 1371) in the presence of the Castilian envoys sent to Portugal by Enrique II.
- Settled in Castile after refusing to pay homage to Queen Leonor Teles on her marriage to his brother Fernando, King of Portugal, and subsequently participated in Castilian incursions into Portugal.
- Joined Enrique II of Castile in 1372, at the onset of the 2nd Guerra Fernandina. [Fernando, ch. 71:12-16]
- In Castile he married Juana, illegitimate daughter of Enrique II and became Lord of Cifuentes.
- When Dinis was still very young, Pedro of Castile proposed a marriage to his daughter Isabel, born from his liaison with María de Padilla (1358). The marriage was not to take place till six years later but, in the event, the plan failed. [Pedro, ch. 15: 38]
Denis