William FitzWilliam, 4th Earl FitzWilliam

William Wentworth-FitzWilliam, 2nd and 4th Earl FitzWilliam (30 May 1748 – 8 February 1833) was a British Whig statesman of the late 18th and early 19th centuries.

Styled Viscount Milton from birth, he inherited the two Earldoms of FitzWilliam (in the Peerages of Great Britain and of Ireland) at the age of eight. Lord FitzWilliam studied at Eton College, where he became friends with Charles James Fox and Lord Morpeth.

FitzWilliam was the nephew of Lord Rockingham, leader of the Old Whig opposition faction in the 1760s and 1770s, and when Rockingham died in 1782, FitzWilliam inherited his estates (making him one of the greatest landowners in the country), as well as taking up his uncle's role as a major leader of the Whigs. In the Lords, FitzWilliam was one of the leading supporters of the Fox-North coalition government, being considerably more effective than the nominal leader of the Government, the Duke of Portland. FitzWilliam was to have become head of the India Board under the Ministry's ill-fated India Bill, but the failure of the Bill led to the fall of the Ministry, and FitzWilliam found himself in opposition.

After the fall of the coalition, FitzWilliam became one of the leading opposition figures in the House of Lords, and generally played the role of a Whig grandee. A fairly conservative Whig, FitzWilliam was horrified by the excesses of the French Revolution, but also concerned to maintain party unity and his own friendship with Fox. FitzWilliam nevertheless supported the war against the French, and agreed with the decision of Portland, the leader of the anti-Foxite Whigs, to break with Fox and his supporters and support Pitt. Nevertheless, FitzWilliam was reluctant for the Portland group actually to join the government, although he ultimately joined on as Lord President in July 1794. Shortly thereafter, he was made also Lord Lieutenant of Ireland. Once in Ireland in January 1795, FitzWilliam caused controversy in the Cabinet by dismissing members of the Irish administration, most notably John Beresford, providing patronage to Irish Whigs and supporting an attempt by Henry Grattan to push through Catholic emancipation. Towards the end of February, Portland wrote to him requesting his return from Ireland.

After his dismissal, FitzWilliam, for which he blamed Portland, returned to opposition and eventually reconciled with Fox. In the Ministry of All the Talents of 1806 to 1807, FitzWilliam was once again Lord President, and then Minister without Portfolio, and he continued as a leading Whig in opposition, although he became gradually less politically involved, and did not join the government when the Whigs finally returned to power in 1830. He died in 1833.