| Pre-Nominals: | The Right Honourable |
| The Earl FitzWilliam | |
| Post-Nominals: | KG |
| Birth Date: | William Thomas Spencer Wentworth-FitzWilliam 12 October 1815 |
| Nationality: | British |
| Spouse: | Lady Frances Harriet Douglas |
| Children: | 14 (including William Wentworth-FitzWilliam, Viscount Milton) |
| Parents: | Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam Hon. Mary Dundas |
William Thomas Spencer Wentworth-FitzWilliam, 6th Earl FitzWilliam, (12 October 1815 – 20 February 1902), styled Hon. William Wentworth-Fitzwilliam 1815–1835, and Viscount Milton 1835–1857, was a British peer, nobleman, and Liberal Party politician.
Wentworth-Fitzwilliam was the second son of Charles Wentworth-FitzWilliam, 5th Earl FitzWilliam and his wife, Hon. Mary Dundas, daughter of Thomas Dundas, 1st Baron Dundas.[1] He was educated at Eton and Trinity College, Cambridge, where he graduated MA in 1837. Two years earlier, his elder brother had died without issue, and he became heir to his father's estates and took the courtesy title Viscount Milton. He became Member of Parliament for Malton in 1837. Holding the seat until 1841, he later reclaimed it in 1846 and then sat for Wicklow from 1847 until 1857, the year he inherited his father's earldom.
He was a JP for the county of the West Riding, DL and a County Councillor for County Wicklow in Ireland.
He held the command of the 1st West Yorkshire Yeomanry Cavalry for 40 years, from 1846–1886, and was a Yeomanry Aide-de-camp to Queen Victoria's Viceroy in India, 1884–1894. Promoted Major for the 3rd battalion Oxfordshire and Buckinghamshire Light Infantry, he also held a number of other military posts. In the territorial army, he was lieutenant-colonel of West Riding RHA with a temporary rank in the British Army during wartime. Lord FitzWilliam was a keen sportsman and continued fox hunting throughout his life. In 1852, under the name of Viscount Milton, he played in a first-class cricket match for Sheffield Cricket Club against Manchester Cricket Club, scoring nine runs in his only innings.[2]
In 1857, Lord FitzWilliam was appointed Lord Lieutenant of the West Riding of Yorkshire and stayed as such until 1892. He was appointed a Knight of the Garter in 1862, and was the senior knight at the time of his death. He died at his residence Wentworth Woodhouse, in Rotherham, on 20 February 1902.[3] As his eldest son predeceased him, his titles passed to his grandson, William Wentworth-Fitzwilliam, 7th Earl of Fitzwilliam. His will was proven on 24 June 1902, with his estate valued at £2,881,619 7s. 4d. (equivalent to £ in).[4]
He owned 115,000 acres, including almost 90,000 in County Wicklow.[5]
On 10 September 1838, Lord Fitzwilliam married Lady Frances Harriet Douglas, the eldest daughter of George Douglas, 17th Earl of Morton. Lady FitzWilliam died on 16 June 1895.[3] They had fourteen children:[1]