Thermo (, before 1915: Κεφαλόβρυσον Kefalovryson) is a town and a municipality in Aetolia-Acarnania, Greece. It is located in the southeastern part of the regional unit, largely between Lake Trichonida (the largest natural lake in Greece) and the southern border of Evrytania. It has a land area of 333.701 km² and a population of 5,712 inhabitants (2021 census). Its municipal seat is the town of Thermo. The village of Megas Dendros (part of the community of Thermo) was the birthplace of Cosmas of Aetolia. Thermo took its name from the ancient city Thermos, that was located near the present town.

Subdivisions

The municipality Thermo consists of the following communities: