William Henry Lawrence Peter Wentworth-Fitzwilliam, 8th Earl Fitzwilliam, DSO (31 December 1910 – 13 May 1948), styled Viscount Milton before 1943, was a British soldier, nobleman, and peer, with a seat in the House of Lords.

[1] During the Second World War, Lord Milton (as he then was) served with distinction in the Commandos and later with the Special Operations Executive, gaining a Distinguished Service Order.

In Lord Fitzwilliam's later years his marriage was in disarray, partly due to Olive's alcoholism,[2] and at the time of his death he was seeking a divorce in order to marry someone else.

[3] From 1946 he had been romantically linked with the widowed Kathleen Cavendish, Marchioness of Hartington, sister of the future U.S. President John F. Kennedy.

[3] On his death, leaving no son, Fitzwilliam's peerages passed to his second cousin once removed, Eric Spencer Wentworth-Fitzwilliam, but his fortune, then estimated at £45 million, including half of the Wentworth Woodhouse estate, the Coolattin estate in County Wicklow, Ireland, and a large part of the Fitzwilliam art collection, were inherited by his thirteen-year-old daughter, the present Lady Juliet Tadgell.