Agnes was born about 1280 in Ulster,Ireland. Agnes' father was Guy O'Cathan. She was an only child. Agnes is no longer alive.
General Notes
The O'Cahans held a large territory called O'Cahan's County in Ulster and claimed descent from Niall of the Nine Hostages, King of Ulster in the 5th century. They were Lords (that is perhaps to say, Celtic chiefs rather than feudal lords) of the Ronte and Princes (again a loose translation of a word for chief, as in the Prince of Coolavin, rather than any formal title) of Limavady before the early 17th-century Plantation of Ulster. [Burke's Peerage, p. 374]