Czartoryski (Polish plural: Czartoryscy) (Ukrainian: Chortoryisky Lithuanian: Cartoriskis) is the surname of a Polish-Ruthenian-Lithuanian magnate family also known as the Familia. They used the Czartoryski coat of arms and were the leading noble family of the Polish-Lithuanian Commonwealth in the 18th century.

The Czartoryski is a family of a Grand Ducal Lithuanian descent from Ruthenia. Their ancestor is the Grand Duke of Lithuania Algirdas's son, known after his baptismal name Constantine (c. 1330 - 1390), who became a Prince of Chortoryisk in Volhynia^{[citation needed]}. One of his sons Vasyli Chortoryiski (Wasyl Czartoryski) (c. 1375 - 1416) was granted an estate in Volhynia in 1393, and his three sons John, Alexander and Michael (c. 1400 - 1489) are considered the progenitors of the family. The founding members were Ruthenian and Eastern Orthodox, and then converted to Roman Catholicism during the 16th century.

It was Michael's descendant Prince Kazimierz Czartoryski (1674–1741) Duke of Klewan and Zukow (Klevan and Zhukiv), Castellan of Vilnius who reawakened their royal ambitions at the end of the 17th century. An intelligent, well educated man^{[citation needed]}, he married Isabella Morsztyn daughter of the Grand Treasurer of Poland and built "The Familia" with their four children, Michał, August, Teodor and Konstancja. The family became known and powerful under the lead of brothers Michał Fryderyk Czartoryski and August Aleksander Czartoryski in the late Polish-Lithuanian Commonwealth of the 18th century, during the reigns of monarchs Augustus II the Strong and Stanisław Leszczyński. The family attained the height of its influence from the mid-18th century in the court of August III of Poland. The Czartoryski brothers gained a very powerful ally in their brother-in-law, Stanisław Poniatowski, whose son became the last king of independent Commonwealth, Stanisław August Poniatowski, near the end of the century.