Harriet Pelham-Holles, Duchess of Newcastle-upon-Tyne (? - 1776) was the wife of the British statesman and Prime Minister Thomas Pelham-Holles, 1st Duke of Newcastle-upon-Tyne. She was the granddaughter of Sir Sidney Godolphin, 1st Earl of Godolphin and the granddaughter of John Churchill, 1st Duke of Marlborough. Until her marriage she was known as Lady Harriet Godolphin. Like her husband she was a devoted Whig and supporter of the Hanoverian succession. They married in April 1717. During the 1720s they became famous for throwing sumptous parties, a tradition that continued for several decades. These were attended even by her husband's political opponents.