Otterøy is a former municipality in the old Nord-Trøndelag county, Norway. The 272-square-kilometre (105 sq mi) municipality existed from 1913 until its dissolution in 1964. It was located in the what is now the municipality of Namsos in Trøndelag county. The former municipality included most of the island of Otterøya (the part south of Tømmervikfjellet mountain), the island of Hoddøya, the southwestern part of the island of Elvalandet, and some of the mainland southwest of Otterøya and Hoddøya. The area contains good farmland and also good salmon fishing. The main church for the area is Otterøy Church.