Sidonius of Saint-Saëns was a seventh-century Irish-born monk who lived and worked in France. Born around 601, he spent much of his life serving within various monastic communities, including a decade in Rome as a companion to Ouen. He is primarily recognized for his role as a spiritual mentor to Leutfridus and for establishing several religious houses in the region. His influence helped shape the monastic landscape of the area during the early medieval period.