William FitzWilliam, 3rd Earl FitzWilliam (15 January 1719/20 – 10 August 1756) was a British peer, nobleman, and politician. He was the son of John Fitzwilliam, 2nd Earl Fitzwilliam by his wife Anne, daughter of John Stringer of Sutton cum Lound, Nottinghamshire. His sister Anne was later second wife to Francis Godolphin, 2nd Baron Godolphin. Lord Fitzwilliam died at Marholm at the age of thirty-six and was succeeded as Earl by his son William. His widow Lady Fitzwilliam died on 29 August 1769.