Murrough O'Brien, 1st Marquess of Thomond Irish Marquess (1726–1808) Parents Mary Jephson James O'Brien Children Mary FitzMaurice, 4th Countess of Orkney Siblings Anne O'Brien Henrietta O'Brien Edward Dominic O'Brien Partners Mary O'Brien, 3rd Countess of Orkney Mary Palmer, Countess of Inchiquin
