Namsen (Norwegian) or Nååmesje (Southern Sami) is one of the longest rivers in Trøndelag county, in the central part of Norway. The 228-kilometre (142 mi) long river flows through the municipalities of Røyrvik, Namsskogan, Grong, Overhalla, and Namsos before emptying into the Namsenfjorden. The river is the namesake for the whole Namdalen region. The river traditionally has been used for floating timber down from the forests to the town of Namsos, where the sawmills were located. Today, parts of the Namsen are regulated by several dams.

Trøndelag (Urban East Norwegian: [ˈtrœ̂ndəˌlɑːɡ]; or Trööndelage  is a county and coextensive with the Trøndelag region in the central part of Norway. It was created in 1687, then named Trondhjem County ; in 1804 the county was split into Nord-Trøndelag and Sør-Trøndelag by the King of Denmark-Norway, and the counties were reunited in 2018 after a vote of the two counties in 2016.