Didacus of Alcalá was a 15th-century Spanish Franciscan lay brother and missionary who served in the Canary Islands. Born in San Nicolás del Puerto around 1400, he initially lived as a wandering hermit before joining the Observant branch of the Franciscan Order. He was known for his missionary work among the Guanche people and his service as an infirmarian in Rome. He died in Alcalá de Henares in 1463 and was later canonized by Pope Sixtus V, becoming the first lay brother of his order to be recognized as a saint.