Background
He was born in Ennistymon, County Clare, to Capt. Edward Dominic O'Brien and Mary Carrick.
He was born in Ennistymon, County Clare, to Capt. Edward Dominic O'Brien and Mary Carrick.
He was created Baron Tadcaster in the British Peerage in 1826. William O'Brien married Elizabeth Rebecca Trotter (1775–1852), daughter of Thomas Trotter of Duleek co Meath on 16 September 1799. They had no son but four daughters:
Sarah married Major William Stanhope Taylor
Mary married Richard White, Viscount Berehaven who succeeded as 2nd Earl of Bantry
Elizabeth married George Stucley Bucke who in 1859 was made Sir George Stucley Stucley, 1st Baronet.