Declán of Ardmore was a 5th-century Irish abbot and priest from Munster. He is primarily recognized for his role in converting the Déisi people to the Christian faith. During his ministry, he established the monastery at Ardmore, located in present-day County Waterford. As a prominent figure in early Irish Christianity, he is often grouped with other Munster saints who are said to have introduced the religion to the region before the arrival of Saint Patrick.