Hattfjelldal (Norwegian) or Aarborte (Southern Sami) is a municipality in Nordland county, Norway. It is part of the Helgeland traditional region. The administrative centre of the municipality is the village of Hattfjelldal. Other villages include Grubben, Svenskvollen, and Varntresk. Hattfjelldal Airfield is located in the village of Hattfjelldal.

Southern or South Sámi is the southwesternmost of the Sámi languages, and is spoken in Norway and Sweden. It is an endangered language; the strongholds of this language are the municipalities of Snåsa, Røyrvik, Røros and Hattfjelldal in Norway. Of the approximately 2000 Southern Sami, only about 500 still speak fluent Southern Sami. This language belongs to the Saamic group within the Uralic language family.