Aerdeyrn

Saint Aerdeyrn was a semi-⁠legendary Welsh saint of the 6th century. He was a descendant of Vortigern and so related to the royal house of Powys. He was the brother of Saints Edeyrn and Elldeyrn, with whom he is often linked.

His name comes from a Celtic word meaning "prince". He built churches in Glamorgan and is the patron of Llanelldeyrn in Wales. No other reliable reports survive. He is honored as a saint of the undivided Church, in the old Welsh calendars.