Léonien de Vienne was a 5th-century monk and abbot who lived in Gaul for over forty years. Originally born in Savaria, located in Pannonia, he was taken as a prisoner by the Burgundians and brought to Autun around 487. After his release, he lived as a hermit, interacting with people from a secluded cell. His reputation for holiness eventually led him to Vienne, where he established monastic communities and served as a spiritual intermediary for the local population.