Flatanger is a municipality in Nord-Trøndelag county, Norway. It is part of the Namdalen region. The administrative centre of the municipality is the village of Lauvsnes. Other villages include Jøssund and Vik.Flatanger was established as a municipality on 1 January 1871 when it was separated from the large municipality of Fosnes. Initially, Flatanger had 1,472 residents. It is one of the few municipalities in Norway whose boundaries have not changed since it was established.
The municipality is named after the old name for one of the fjords in the area, but it is not known which one. The name is composed of two parts: flat, which probably means "shallow water", and angr, which means "fjord or inlet".The coat-of-arms is from modern times; they were granted in 1990. The arms show three silver chevrons on a green background. The design was chosen to represent the bow of a boat, seen from the front.