Saint Nonnosus (c. 500 – 560 AD), also Nonosius, was a prior at the San Silvestre monastery on Monte Soratte north of Rome and later a monk at Suppentonia, near Civita Castellana. He was a contemporary of Saint Benedict of Nursia. Alban Butler has written that “so little information has survived about Nonnosus that he is not especially interesting in himself.” His name does not appear in any ancient martyrology.