William Fairfax (1691–1757) was a political appointee of the British Crown and a politician: he was Collector of Customs in Barbados, and Chief Justice and governor of the Bahamas; he served as Customs agent in Marblehead, Massachusetts before being reassigned to the Virginia colony.
There he was elected to the House of Burgesses and then as President of the Governor's Council. As a tobacco planter, he commissioned the construction of his plantation called Belvoir in northern Virginia. He was the son of Henry Fairfax (d. 1708), a grandson of Henry Fairfax, 4th Lord Fairfax of Cameron, and first cousin of Thomas Fairfax, 6th Lord Fairfax of Cameron. He acted as land agent for his cousin's vast holdings on the Northern Neck of Virginia.
William Fairfax was born in London in 1691, the son of Henry Fairfax and grandson of Henry Fairfax, 4th Lord Fairfax of Cameron. As a young man, he went to the English colonies in the Caribbean, where he served as the Customs agent in Barbados and as Chief Justice of the Bahamas under Woodes Rogers. He served as governor of the Bahamas after Rogers' departure.
William was the cousin of Thomas Fairfax, 6th Lord Fairfax of Cameron, proprietor of the extensive grant of land on the Northern Neck of Virginia. Residing in England in Leeds Castle, Lord Fairfax used a succession of land agents to manage his vast Virginia property. Upon reading the 1732 obituary of his last resident agent, Robert "King" Carter, and learning of the vast personal wealth Carter had amassed, Lord Fairfax decided to place a trusted member of the family in charge of his 5-million-acre (20,000 km2) Northern Neck proprietary.