 William O'Brien, 3rd Earl of Inchiquin

William MacWilliam O'Brien, 8th Baron of Inchiquin, 3rd Baron O'Brien of Burren, 3rd Earl of Inchiquin PC (1662 – 24 December 1719) was an Irish nobleman.William O'Brien was the son of William O'Brien, 2nd Earl of Inchiquin and Lady Margaret Boyle.