Rissa is a former municipality in the old Sør-Trøndelag county in Norway in the Fosen region. The municipality existed from 1860 until its dissolution on 1 January 2018 when it became part of the municipality of Indre Fosen in Trøndelag county. The administrative centre of the municipality was the village of Årnset. Other villages in the municipality included Askjem, Hasselvika, Husbysjøen, Rørvika, Råkvåg, and Stadsbygd.

Sør-Trøndelag was a county comprising the southern portion of the present-day Trøndelag county in Norway. It bordered the old Nord-Trøndelag county as well as the counties of Møre og Romsdal, Oppland, and Hedmark. To the west is the Norwegian Sea, and to the east is Jämtland in Sweden. The county was separated into a northern and southern part by the Trondheimsfjord. Slightly over 200,000 of the county's population lives in the city of Trondheim and its suburbs. The Norwegian dialect of the region is Trøndersk.