Jehan Vaillant (fl. 1360–1390; also spelled Johannes Vayllant) was a French composer and music 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".[1] 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 and P. des Molins, 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.[2]