- (1345–1359) Son of Alfonso XI of Castile and his mistress Leonor Núñez de Guzmán.
- Killed at the age of fourteen by order of his half-brother Pedro King of Castile in the course on his revenge taken on the Guzmán family. His brother Juan Alfonso, aged nineteen, was also killed on the same occasion. [Pedro, ch. 25: 35-38]