Guillaume de Van (2 July 1906 in Memphis – 2 July 1949 in Amalfi) real name William Carrolle Devan, was a French musicologist and choral conductor of American origin. A student at Princeton University, he then traveled to Rome to train in Gregorian chant. In the early 1930s, he became choir conductor, conducting the Armenian choir in Paris. In 1935, in collaboration with abbot Ducaud-Bourget, he founded the vocal ensemble Les Paraphonistes de Saint-Jean des Matines. With this ensemble he interpreted and recorded for the first time several secular and religious vocal works of the Middle Ages. Among these works, he recorded the world premiere of Messe de Nostre Dame by Guillaume de Machaut in 1936 of which he made one of the first complete transcriptions published by the Corpus mensurabilis