- (1364-1435) Daughter of King Fernando of Portugal; born from a liaison before he contracted marriage to Doña Constanza Manuel.
- Married Alfonso Enríquez, natural son of Enrique II of Castile, according to the conditions established by the peace treaty signed in Santarém, in 1373. The marriage, however, only took place in 1375 owing to the young age of the bride. The groom, however, only married Dona Isabel out of fear for his father. They led separate lives and as soon as King Enrique II died, the marriage was annuled.
Isabell