Mary O'Brien (1662-1683) (1662–1683) Parents Henry O'Brien, Lord Ibrackan Katherine Stuart, Baroness Clifton (of Leighton Bromswold) Children Henry FitzGerald, Lord Offaly Siblings Donogh O'Brien, Lord Ibracken Katherine O'Brien, Baroness Clifton (of Leighton Bromswold) George O'Brien Partners John FitzGerald, 18th Earl of Kildare