William O'Brien, 2nd Marquess of Thomond Irish Marquess (1765–1846) Parents Edward Dominic O'Brien Mary Carrick Children Lady Elisabeth O'Brien Lady Susan Maria O'Brien Lady Sarah O'Brien Lady Mary O'Brien Siblings James O'Brien, 3rd Marquess of Thomond Murrough O'Brien John O'Brien Lord Edward O'Brien Harriet O'Brien Mary O'Brien Partners Elizabeth Trotter
