Demandasaurus (meaning "Demanda lizard") is a genus of rebbachisaurid sauropod dinosaur from early Cretaceous (late Barremian – early Aptian stage) deposits of Spain. Demandasaurus is known from an incomplete but associated skeleton that includes cranial and postcranial remains. It was collected from the Castrillo de la Reina Formation in Burgos Province of Spain. It was first named by Fidel Torcida Fernández-Baldor, José Ignacio Canudo, Pedro Huerta, Diego Montero, Xabier Pereda Suberbiola and Leonardo Salgado in 2011 and the type species is Demandasaurus darwini.