Lierne is a municipality in Trøndelag county, Norway. It is part of the Namdalen region, and it is the largest municipality by area in Trøndelag. The administrative centre of the municipality is the village of Sandvika. Other villages include Inderdal, Mebygda, and Tunnsjø senter. The municipality borders Sweden to the south and east. Most of Lierne lies on the Swedish side of the drainage divide between Norway and Sweden.

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.