O’Lonergan, Edmund, [317]
O’Madden, of Longford in Galway, [69], [228], [402]
O’Meagher, of Ikerrin in Tipperary, [211], [242], [321], [329]
O’Melaghlin (commonly corrupted into MacLoughlin), of Clonlonan in Westmeath, [39], [52], [228], [334]
O’Molloy, of Fercall (including Ballyboy and Ballycowan) in King’s County, [206], [211], [226], [262], [338], [402], [403]
O’More, Lysaght, [77]
— Connell, chief of Leix, [132], [175]-[177], [224]