Henrietta "Harriet" Pelham-Holles, Duchess of Newcastle upon Tyne and Duchess of Newcastle-under-Lyne (1701 – 17 July 1776), was the wife of British statesman and prime minister Thomas Pelham-Holles, 1st Duke of Newcastle.

She was also the granddaughter of Sidney Godolphin, 1st Earl of Godolphin, as well as John Churchill, 1st Duke of Marlborough, and Sarah Churchill, Duchess of Marlborough.

Like her husband, she was a devoted Whig and supporter of the Hanoverian succession.

[3] During the 1720s, they became famous for throwing sumptuous parties, a tradition that continued for several decades; these were attended even by her husband's political opponents.

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