- Prior of Guadalupe and Chancellor of the Privy Seal.
- Juan I of Castile sent him, the doctor in canon and civil law Álvaro Martínez de Villareal, and the knight Diego López de Medrano with his reply to the Duke of Lancaster when the latter arrived in Galicia and sent the king a message claiming the crown of Castile for his wife and himself (1386).
- Bibl: M. D. J. M., Historia Del Reinado de D. Pedro Primero de Castilla (Sevilla: Cários Santigosa, 1847), p. 182.
Joham Serano
Chronicle entries in which Juan Serrano, Prior of Guadalupe appears:
Crónica de D. João I, part 2, ch. 84