O'Brien, William, 4th Earl of Inchiquin (1700 -1777)
O'Brien was the eldest son of William O'Brien, 3rd Earl of Inchiquin, 8th Baron Inchiquin, and Mary Villiers, sister of the 1st Earl of Jersey. He inherited his father's titles in 1719. On 29 March 1720, he married his cousin, Lady Anne Hamilton, the eldest daughter and heiress of George Hamilton, 1st Earl of Orkney, and Elizabeth Villiers. His wife became 2nd Countess of Orkney in her own right in 1737. They had five children. Inchiquin was Whig Member of Parliament for Windsor 1722-1727, for Tamworth 1727-1734, for Camelford 1741-1747 and for Aylesbury 1747-1754. In 1725, he had been appointed a Knight Companion of the Order of the Bath. From 1740 to 1741, he was Grand Master of the Premier Grand Lodge of England, Governor of County Clare 1741-1777 and Custos Rotulorum of County Clare 1762-1767. He was a Lord of the Bedchamber to Frederick, Prince of Wales 1744-1751, and was admitted to the Privy Council of Ireland in 1753. On his death in 1777, without surviving male heirs, his titles passed to his nephew, Murrough O'Brien, who was later created Marquess of Thomond.