Tønder is a town in the Region of Southern Denmark. With a population of 7,574, it is the main town and the administrative seat of the Tønder Municipality.

Tønder Municipality is a kommune in the Region of Southern Denmark on the Jutland peninsula in south Denmark. The municipality covers an area of 1,252 km2, and has a total population of 36,878 (2023). Its mayor is Jørgen Popp Petersen, a member of the regional Schleswig Party.