Grimace (also Grymace or Grimache) was a French composer active in the mid-to-late 14th century. Grimace was active in the period of music history known as the ars nova and was probably a contemporary of Guillaume de Machaut, since his compositions lack the complicated rhythms of the Ars subtilior. Grimace's birth and death dates are not known; little is known about him outside of attributions in medieval music manuscripts. Five works are attributed to him securely; two doubtful attributions have been proposed based on stylistic similarities. His virelai, A l'arme, A l'arme, is his most often performed work in modern times.