Nonnosus was a sixth-century monk and Benedictine prior who lived near Rome. A contemporary of Saint Benedict, he served as the prior of the San Silvestre monastery on Monte Soratte before later becoming a monk at Suppentonia. Although he is not recorded in ancient martyrologies, he is recognized as a saint within the Catholic tradition. His historical identity may involve the merging of two distinct figures, and he is also mentioned as a deacon in certain Carinthian legends.