Massat (French pronunciation: [masat]) is a commune in the Ariège department in southwestern France.

The area dates back to paleolithic times, when tribes left some traces in painted caves in the Ker valleys of Massat.

From 1820, with the discovery of the means of melting iron with coal, the industrial prosperity of the valley disappeared.

Later in the 19th century, agricultural, primarily pastoral farming became the main source for the Massat economy, particularly the production of butter.

With a very strong rural migration, amplified by World War I, the valley depopulated quickly, falling dramatically from 17,000 inhabitants in 1800 to just 1700 in total today, and just 589 in the village.