Telemark [ˈtêːləmɑrk] (listen) is a traditional region, a former county, and a current electoral district in southern Norway. In 2020, Telemark merged with the former county of Vestfold to form the county of Vestfold og Telemark. Telemark borders the traditional regions and former counties of Vestfold, Buskerud, Hordaland, Rogaland and Aust-Agder.

The name Telemark means the "mark of the Thelir", the ancient North Germanic tribe that inhabited what is now known as Upper Telemark in the Migration Period and the Viking Age.

In the Middle Ages, the agricultural society of Upper Telemark was considered the most violent region of Norway. Today, half of the buildings from medieval times in Norway are located here. The dialects spoken in Upper Telemark also retain more elements of Old Norse than those spoken elsewhere in the country. Upper Telemark is also known as the birthplace of skiing.

The southern part of Telemark, Grenland, is more urban and influenced by trade with the Low Countries, northern Germany, Denmark and the British Isles.

Telemark has been one of Norway's most important industrial regions for centuries, marked in particular by the Norske Skog Union paper mills in Grenland and the Norsk Hydro heavy water and fertilizer production in Upper Telemark.

Telemark as a county is expected to be re-established by 1 January 2024, following a vote of the county council of Vestfold og Telemark on 15 February 2022 to split the newly established county into its respective counties that existed before the merger took place; Telemark and Vestfold.