William Fairfax (1691–1757) was a political appointee of the British Crown in several colonies as well as a planter and politician in the Colony of Virginia. Fairfax served as Collector of Customs in Barbados, Chief Justice and governor of the Bahamas; and Customs agent in Marblehead, Massachusetts, before being reassigned to the Colony of Virginia.

Belvoir was the plantation and estate of colonial Virginia's prominent William Fairfax family. Operated with the forced labor of enslaved people, it was located on the west bank of the Potomac River on the present site of Fort Belvoir in Fairfax County, Virginia.