William O'Brien, 3rd Earl of Inchiquin Irish Earl (1662–1719) Parents William O'Brien, 2nd Earl of Inchiquin Margareth Boyle Children Lady Mary O'Brien Lady Henrietta O'Brien Charles O'Brien James O'Brien William O'Brien, 4th Earl of Inchiquin Siblings Lady Margaret O'Brien unknown son O'Brien Henry O'Brien Partners Mary Villiers Margaret O'Brien
