Jules Gros, Jul Marcel Gros (1890 – 1992) was a Breton linguist specializing in popular language. He was born in Paris.
Gros' collecting, from his grandmother and other people in his village of Lokémo, began very early at beginning of the twentieth century. At this time there were still unilingual Breton speakers. Gros authored Stylistique Trégorroise and various dictionaries. He was a resource for a whole generation of young students of Breton. His works are also valuable to modern students of Breton. With the death of former generations who spoke only Breton, reference works cataloguing their speech patterns take on a new importance. Because of this, his works will remain a major reference. He died in Trédrez-Locquémeau.