Guillaume Sanson (1633 - 1703) was a French cartographer active in the latter part of the 17th century. He is the son of the legendary cartographer Nicolas Sanson (1600 - 1667), and, along with his brother Adrien Sanson (1639 - 1718), took over the family firm on his father's death. Like his father, Guillaume Louis XIV granted him the official title, Geographe Ordinaire du Roy. Much of his work after 1671 was published in collaboration with Alexis-Hubert Jaillot (c. 1632 - 1712). Although the continued to published new maps, particularly Guillaume Sanson, the firm began to lose prestige and market share. In 1692, the brothers sold their geographical archive to their nephew Pierre-Moulart Sanson (1670 - 1730), who published a map catalog in 1696 and reissued the Sanson atlas. After Pierre-Moulart's death, many of the surviving map plates were acquired by Gilles Robert de Vaugondy, setting the stage for another French cartographic dynasty.