William Thornton (December 20, 1717 – 1790) was a planter and public official in Colonial Virginia. Thornton served as member of the House of Burgesses for Brunswick County from 1756–68 and as justice of the county and of the quorum as early as 1760 and as late as 1774/5. Thornton was the great-grandson of William Thornton who arrived in Virginia from England as late as 1646 settling in Gloucester County, Virginia. He was through his paternal line a cousin of fellow burgesses, Francis Thornton of Spotsylvania, Presley Thornton of Northumberland, George Thornton of Spotsylvania, William Thornton of King George and William Thornton of Richmond County, Virginia.