O'BYRNE. "The O'Byrncs were the formidable chieftains of that last subjugated district of Ireland, now tlie county of Wicklow ; the present barony of Ballinacor and the Ranilogh were possessed exclusively by them, and they, with the O'Tooles, the territorial lords of the remainder of this county,maintained,for nearly four centuries, an unceasing war against Dublin and the English Pale." The surname first appears in 1119. D'Alton.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.