Jehan Vaillant (fl. 1360–1390; also spelled Johannes Vayllant) was a French music composer and theorist. He is named immediately after Guillaume de Machaut by the Règles de la seconde rhétorique, which describes him as a "master … who had a school of music in Paris". Besides five (possibly six) pieces of music surviving to his name, he was also the author of a treatise on tuning. With Grimace and F. Andrieu, Vaillant was part of the post-Machaut generation whose music shows few distinctly ars subtilior features, leading scholars to recognize Vaillant's work as closer to the ars nova style of Machaut.