Hester Pitt, Countess of Chatham (8 November 1720 – 9 April 1803), 1st Baroness Chatham in her own right, was the wife of William Pitt (the Elder), 1st Earl of Chatham, who was Prime Minister of Great Britain from 1766 to 1768. and sister of George Grenville, who was Prime Minister of Great Britain from 1763 to 1765. She was also a niece of the noted Whig politician Richard Temple, 1st Viscount Cobham, who had served as William Pitt's mentor.