CHÂTEAUBRIANT, a town of France, at the head of an arrondissement in the department of Loire Inférieure, on the left bank of the Chère, a tributary of the Vilaine, 35 miles N.N.E. of Nantes. It takes its name from a castle founded in 1015 by Briant, count of Penthièvre; and its principal ornament is another castle,built in 1524by Jean de Laval, and famous in history as the scene of the assassination of Françoise de Foix. There is also an interesting Romanesque church dedicated to St Jean de Bère. The manufactures are mainly woollen stuffs and confectionery; and the trade is in iron, coal, and wood. Population in 1872, 4134.