Xavier de Langlais (April 26, 1906, Sarzeau – June 15, 1975) was a Breton painter, printmaker and writer. He usually signed his work with the name Langleiz, a Breton language version of his surname.
Langlais studied art in Nantes (1922) and Paris (1926–1928). During his stay in Paris he took advantage of his free time to learn the Breton language. He tried to find a way to create a new art connected with his love of Brittany, and began to work as a painter, church decorator and researcher into artistic techniques.
In 1931 he married Annick Gazet du Chatelier, with whom he had four children. In 1948, he became a professor of design at the Ecole des Beaux-Arts de Rennes, where he continued to work for the remainder of his career. He also worked as an illustrator, mainly using the traditional woodblock printing technique.
He wrote a book on techniques of oil painting, which is still authoritative and has been translated into several languages.
A supporter of the Breton National Party, he edited and illustrated its literature. In 1924, he made contact with Ar Seiz Breur, a group of nationalistic Breton artists formed by Jeanne Malivel and René-Yves Creston.
With James Bouillé, an architect and member of Ar Seiz Breur, he established the art workshop "An Droellenn" (The Spiral) in 1935. This was dedicated to the revival of Breton Christian art. He created several religious murals: in the chapel of St. Joseph's College in Lannion, the Grand Seminary in Saint-Brieuc, the Notre-Dame-de-la-Mer Étel Church in La Richardais, and the stations of the cross, La Baule.
He was a prolific writer in the Breton language and was an ardent promoter of orthographic reform would create characters for the specific dialect of Vannes Breton that he practiced. He held discussions in Vannes in 1936, but the project only reached fruition 1941. In that year he moved to Rennes, where he worked as an artistic and literary critic, writing a regular column in La Bretagne, a pro-Marshal Philippe Pétain collaborationist newspaper edited by Yann Fouéré.