Erc was king of Irish Dál Riata from 439 until 474, succeeding Eochaid Muinremuir.
Suggestions that he was identical with Muiredach mac Eógain and thus belonged to the Uí Néill are based on late sources, such as the Annals of the Four Masters.
It is typical in late genealogies for unrelated peoples or those only related through marriage to be worked into a single genealogical scheme and all be made descendants of the same legendary founder.
Erc is significant as he has been traditionally regarded as the ancestor, through his son Fergus Mor, of the kings of Dalriada, and through them the Kings of Scotland, but more recently much of this tradition has been questioned.
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