Namsos is a municipality in Nord-Trøndelag county, Norway. It is part of the Namdalen region. The administrative centre of the municipality is the town of Namsos. Other villages in the municipality include Bangsund, Klinga, Ramsvika, Skomsvoll, and Spillum. The municipality has a population of 12,906 and covers and area of 777.89 square kilometers (300.35 sq mi).
The first part of the name comes from the local river Namsen. The last element is os, which means the "mouth of a river".
The coat-of-arms is from modern times; they were granted on 5 May 1961. The arms show a yellow moose on a red background. The moose was chosen as a symbol for the municipality, since Namsos is the capital of the forest-rich Namdalen region, and the moose is the "king of the forest".The Church of Norway has four parishes (sokn) within the municipality of Namsos. It is part of the Namdal deanery in the Diocese of Nidaros.