Medievalist and enamels specialist, curator of the Louvre Museum. Marquet was the son of Louis Marie Léon Marquet de Vasselot (1836-1918), an industrialist. Marquet studied at the Collège Stanislas, then the Faculté des Lettres de Paris, receiving his Licencié de lettres in 1892. He continued at the école du Louvre for a diplôme in 1896. He married Jehanne Martin Le Roy, daughter of the art collector Victor Martin Le Roy (1842-1918).