Ferdinand the Holy Prince was a 15th-century Portuguese infante and a member of the House of Aviz. As the youngest son of King John I, he was part of the so-called illustrious generation of princes. He served as the lay administrator for the Knightly Order of Aviz and was known for his deep piety. Following a failed military expedition to Tangier in 1437, he was taken as a hostage by the Marinid rulers to ensure the return of Ceuta, eventually dying in captivity in Fez.