William Ambroise Marçais (6 November 1872, Rennes – 1 October 1956, Paris), was a French Orientalist, particularly noted as an expert on the Maghrebi Arabic dialects.
Soon after his successful graduation and as he was contemplating a career in the diplomatic service, his lecture of the works of Ernest Renan turned him towards the study of the Semitic languages.
[2] In the same year he assumed the position of director of the madrasa of Tlemcen in French Algeria.
In 1904 he became director of the madrasa of Algiers, five years later advanced to the position of inspector general of the education system for the native population, and in 1913 he was named as director of the École supérieure de langue et littérature arabe at Tunis.
[2] In 1916, he returned to Paris, where he became teacher of vulgate Arabic at the École des langues orientales, rising to professor in 1920.