Cosa is a municipality in the province of Teruel, within the autonomous community of Aragon, Spain. It is one of the many small settlements that make up the sparsely populated Teruel province in northeastern Spain.
The municipality is notable for its very small population. According to the 2006 census conducted by the Instituto Nacional de Estadística (INE), Cosa had a population of 87 inhabitants. This figure places it among the many rural municipalities in the region that have experienced significant depopulation, a pattern common across inland Aragon.
As a municipality, Cosa holds the administrative status of a local entity within the Spanish system of government, encompassing its surrounding territory and residents under a local council. Its small size and location in Teruel province mean it shares the characteristics of other similarly sized Aragonese municipalities: a rural setting and a population counted in the dozens rather than thousands.