Sarah "Sally" Cary Fairfax (c.1735 – 1811 in Bath, England) was the wife of George William Fairfax (1724–1787), a prominent member of the landed gentry of late colonial Virginia, and the mistress of the Virginia plantation and estate of Belvoir. She is well-remembered for being the woman George Washington was apparently in love with before his marriage to Martha Dandridge Custis.