Percy Wyndham-O'Brien, 1st Earl of Thomond (c. 1713 – 1774) was a British Member of Parliament, Irish peer and the younger son of Tory statesman Sir William Wyndham and brother to Sir Charles Wyndham, 2nd Earl of Egremont.
In 1741, Henry O'Brien, 8th Earl of Thomond died without issue and in his will left the entire Irish estates of the Earls of Thomond to his nephew Percy Wyndham, the younger son of his wife's sister. In compliance with the terms of his inheritance, Percy took the additional name of O'Brien and was created Earl of Thomond and Baron Ibracken in the second creation on 11 December 1756.
He was MP for the constituency of Taunton in Somerset from 1745 to 1747 when he was succeeded by his brother Sir Charles Wyndham.
When Percy died unmarried and without issue in 1774 the title again became extinct. The lands passed to his nephew George Wyndham, 3rd Earl of Egremont of Petworth House.
| Parliament of Great Britain | ||
|---|---|---|
| Preceded by Sir John Chapman, Bt John Buck |
Member of Parliament for Taunton with Sir John Chapman, Bt 1745–1747 |
Succeeded by Sir Charles Wyndham Robert Webb |
| Preceded by Thomas Carew John Periam |
Member of Parliament for Minehead with Charles Whitworth 1747–1754 |
Succeeded by Charles Whitworth Daniel Boone |
| Preceded by Sir John Mordaunt William Finch |
Member of Parliament for Cockermouth with Sir John Mordaunt 1754–1761 |
Succeeded by Sir John Mordaunt Charles Jenkinson |
| Preceded by Arnold Nesbitt Thomas Orby Hunter |
Member of Parliament for Winchelsea with Thomas Orby Hunter 1761 |
Succeeded by Thomas Orby Hunter Thomas Sewell |
| Preceded by Charles Whitworth Daniel Boone |
Member of Parliament for Minehead with Henry Shiffner 1761–1768 |
Succeeded by Henry Fownes-Luttrell Sir Charles Whitworth |
| Preceded by Thomas Orby Hunter Thomas Sewell |
Member of Parliament for Winchelsea with Thomas Orby Hunter 1768–1770 Arnold Nesbitt 1770–1774 1768–1774 |
Succeeded by Arnold Nesbitt William Nedham |
| Political offices | ||
| Preceded by The Viscount Bateman |
Treasurer of the Household 1757–1761 |
Succeeded by The Earl of Powis |
| Preceded by James Grenville |
Cofferer of the Household 1761–1765 |
Succeeded by The Earl of Scarbrough |
| Honorary titles | ||
| Preceded by The Earl Poulett |
Lord Lieutenant of Somerset 1764–1774 |
Succeeded by Lord North |
| Peerage of Ireland | ||
| New creation | Earl of Thomond 1756–1774 |
Extinct |