Acheloos () is a former municipality in the Karditsa regional unit, Thessaly, Greece. Since the 2011 local government reform it is part of the municipality Argithea, of which it is a municipal unit. The municipal unit has an area of 87.430 km<sup>2</sup>. It is named after the Acheloos River. Population 913 (2021). The seat of the municipality was in Vragkiana.