Percy Wyndham-O'Brien, 1st Earl of Thomond

Percy Wyndham O'Brien, 1st Earl of Thomond (* 1723, † July 21, 1774 ) was an Irish peer and British politician.

Percy Wyndham was born in 1723 as a younger son of William Wyndham and Katherine Seymour. He attended from 1737 to 1740 the Westminster School and then St Mary Hall, Oxford, then he went on a Grand Tour. He inherited on September 20, 1741 lying mainly in Ireland, the goods of his uncle Henry O'Brien, 7th Earl of Thomond, who was married to the sister of his mother, and therefore added its name to Wyndham O'Brien. From 1745 to 1747 he was a delegate in the House of Commons for Taunton, 1747-1754 Minehead, 1754-1761 Cockermouth, from 1761 to 1768 again for Minehead and from 1768 until his death in Winchelsea.

He almost never appeared as a speaker in parliament in appearance, but supported his brother Charles Wyndham and his brother George Grenville politics. Several times he had held high government and court offices, he was from December 1755 to November 1756 a Lord Commissioner of the Treasury. With the government takeover of Cavendish he lost his position, so he was awarded Cavendish on December 11, 1756 the title of 1st Earl of Thomond. However, since this title was in the Peerage of Ireland, no seat stood him in the House of Lords and Wyndham was a deputy in the House of Commons. From July 1757 to November 1761, he held the court office of the Treasurer of the Household, for which he was also a member of the Privy Council on July 8, 1757. From 1761 to 1765 he was Cofferer of the Household, and from 1764 until his death, Lord Lieutenant of Somerset.

Wyndham remained unmarried, after the untimely death of his brother in 1763 he became guardian of his twelve year old nephew George. He lived mainly in London or on his English goods, and almost never visited his property in Ireland. He died on July 21, 1774 of a stroke. The title Earl of Thomond became extinct with his death, his estate was inherited by his nephew George Wyndham, who is also the name of O'Brien inflicted on his behalf.