Thomas Fairfax (1762–1846), landowner, was a native of Virginia who inherited large tracts of land in the northern part of the state and lived the majority of his life in Fairfax County and Alexandria. In 1802 he became 9th Baron Fairfax of Cameron, but he evidently did not use the Scottish title. Fairfax built a house called Ash Grove in Fairfax County in about 1790, and he later moved to another property in the county called Vaucluse, giving Ash Grove to a son. In religion he was a Swedenborgian. Fairfax supported the American Colonization Society and emancipated several slaves during his lifetime. In 1840 five slaves, possibly rented, lived in his household. Fairfax died at Vaucluse. He left an extensive estate, including a house and lot in Alexandria, stock, and bank shares (Kenton Kilmer and Donald Sweig, The Fairfax Family in Fairfax County [1975], 43, 46, 48; Louise Pecquet du Bellet, Some Prominent Virginia Families [1907], 2:177–8; WMQ description begins William and Mary Quarterly, 1892–  description ends , 1st ser., 18 [1910]: 283–6; 2d ser., 7 [1927]: 87, 89, 90; Donald Jackson and Dorothy Twohig, eds., The Diaries of George Washington [1976–79], 5:17; Washington, Papers, Pres. Ser., 12:442; Fairfax, Journey from Virginia to Salem, Massachusetts, 1799 [1936]; DNA: RG 29, CS, Fairfax Co., 1810, 1820, 1840, Alexandria, 1830; American Society for Colonizing the Free People of Colour of the United States [later the American Colonization Society], Annual Report 14 [1831]: unnumbered page following p. 32; Alexandria Gazette, 23 Apr. 1846; Fairfax Co. Will Book, U:382–5, X:205–22, Z:208–9; gravestone inscription in Ivy Hill Cemetery, Alexandria).

Fairfax’s three sons, Orlando Fairfax, Henry Fairfax, and Albert Fairfax, were among the earliest students at the University of Virginia (Nash, Students of the University of Virginia).