Naut Aran (Occitan pronunciation: [ˈnawt aˈɾan]) is a municipality in the comarca of the Aran Valley in Catalonia, Spain. It is the second largest municipality in Catalonia in terms of surface area (225.8 km², behind Tremp), and was created in 1967 by the merger of the municipalities of Arties, Salardú, Gessa, Tredòs and Bagergue: the former municipalities retain some privileges as "decentralised municipal entities" (entitats municipals descentralitzades, EMD).