Jean-Nicolas Boulay (11 June 1837 in Vagney – 19 October 1905 in Lille) was a French clergyman, bryologist and paleobotanist. He studied theology at the seminary in Saint-Dié-des-Vosges, later being named professor of botany at the Catholic University of Lille (1875). The Jardin botanique Nicolas Boulay at the university is named in his honor.