William Fitzwilliam, 3rd Earl Fitzwilliam

William Fitzwilliam, 3rd Earl Fitzwilliam, was born either in 1719 or 1720, and died on 10 August 1756. He was a British peer, nobleman, and politician, the son of John Fitzwilliam, 2nd Earl Fitzwilliam, and his wife Anne, daughter of John Stringer of Sutton cum Lound, Nottinghamshire. His sister was Anne Fitzwilliam, who became the second wife of Francis Godolphin, 2nd Baron Godolphin.

William Fitzwilliam succeeded his father as the third Earl Fitzwilliam in the Peerage of Ireland on 28 August 1728. He was elected as the Member of Parliament for Peterborough on 4 May 1741. The following year, on 19 April 1742, he was created Baron Fitzwilliam in the Peerage of Great Britain. He was appointed to the Irish Privy Council on 6 June 1746. Later that year, on 6 September 1746, he was further elevated in peerage as Earl Fitzwilliam in the Peerage of Great Britain.

On 22 June 1744, William Fitzwilliam married Lady Anne Watson-Wentworth at St George's, Hanover Square. Lady Anne was the daughter of the Earl of Malton, who was later elevated to the Marquess of Rockingham. Her brother was Charles Watson-Wentworth, the future Prime Minister of Great Britain.

The marriage produced two sons and six daughters. Their children included Lady Anne (born 23 March 1745, died 8 December 1819), Lady Charlotte (born 14 July 1746, died 11 February 1833), who married Thomas Dundas, 1st Baron Dundas, on 24 May 1764, and had issue. Their son, William Fitzwilliam, succeeded as the 4th Earl Fitzwilliam, born 30 May 1748 and died 8 February 1833. Other children were Lady Frances Henrietta (born 22 October 1750, died 28 October 1835), Lady Amelia Maria (born 12 December 1751, died 8 August 1752), Lady Henrietta (born 20 March 1753), Lady Dorothy (born 22 May 1754, died 16 March 1809), and George Fitzwilliam (born 28 February 1756, died May 1786).

William Fitzwilliam died at Marholm at the age of approximately 36. His son William succeeded him as the 4th Earl Fitzwilliam. His widow, Lady Anne, died on 29 August 1769.