Fjergen is a lake in Meråker Municipality in Trøndelag county, Norway. The 14.41-square-kilometre (5.56 sq mi) lake has a hydropower dam on the southern end which flows out into the Kåpperåa river which is part of the Stjørdalselva river system. There is about 204,000,000 cubic metres (7.2×10 cu ft) of water stored in the lake.

The lake is located about 5 kilometres (3.1 mi) north of the village of Kopperå and about 7 kilometres (4.3 mi) northeast of the municipal center of Midtbygda. The lakes Feren and Funnsjøen lie several kilometers to the northwest, and the border with Sweden lies a few kilometers to the east.

• List of lakes in Norway