Earl Fitzwilliam

Earldom of Fitzwilliam
Quarterly, 1st and 4th: Lozengy argent and gules (Fitzwilliam); 2nd and 3rd: sable, a chevron between three leopards' faces, or (Wentworth)
Creation date	1716 (Ireland) 1746 (Great Britain)
Monarch	George I (Ireland) George II (Great Britain)
Peerage	Peerage of Ireland Peerage of Great Britain
First holder	William Fitzwilliam, 3rd Baron Fitzwilliam
Last holder	Thomas Wentworth-Fitzwilliam, 10th Earl Fitzwilliam
Remainder to	Heirs male of the first earl's body lawfully begotten
Subsidiary titles	Viscount Milton Baron Fitzwilliam
Extinction date	21 September 1979
Former seat(s)	Wentworth Woodhouse Milton Hall
Armorial motto	Appetitus rationi pareat ("Let your desires be ruled by reason")

Earl Fitzwilliam (or FitzWilliam) was a title in both the Peerage of Ireland and the Peerage of Great Britain held by the head of the Fitzwilliam family (later Wentworth-Fitzwilliam).

The Fitzwilliams acquired extensive holdings in the south of the West Riding of Yorkshire, largely through strategic alliances through marriage. In 1410, Sir John Fitzwilliam of Sprotborough, who died in 1421, married Margaret Clarell, daughter of Thomas Clarell of Aldwark, the descendant of a major Norman landholding family. This is how the Fitzwilliams acquired the Clarell holdings.

Sir William Fitzwilliam (c. 1460–1534) was an Alderman and Sheriff of London and acquired the Milton Hall estate in Peterborough in 1502. His grandson Sir William Fitzwilliam served as Lord Deputy of Ireland from 1571 to 1575 and from 1588 to 1594; he supervised the execution of the death sentence on Mary, Queen of Scots.

His grandson William Fitzwilliam (d. 1643) was raised to the Peerage of Ireland as Lord Fitzwilliam, Baron of Liffer, alias Lifford, in the County of Donegal, in 1620. He was the first Baron FitzWilliam.

His son was William FitzWilliam, 2nd Baron FitzWilliam (c.1609 – 21 February 1658).

His son William became 3rd Baron FitzWilliam.

The 3rd Baron FitzWilliam succeeded his father in 1658, and in 1716 was created the first Earl Fitzwilliam, of the County of Tyrone with the subsidiary title Viscount Milton, in the County of Westmeath, also in the Peerage of Ireland. The eldest son of the Earl Fitzwilliam bore the courtesy title Viscount Milton. He was succeeded by his son, the second Earl.

The second Earl, John Fitzwilliam, sat as Member of Parliament for Peterborough. On his death the titles passed to his son, the third Earl.