Tønder (German: Tondern, North Frisian: Tuner) is a municipality (Danish, kommune) in Region of Southern Denmark on the Jutland peninsula in south Denmark. The municipality covers an area of 1,278 km², and has a total population of 40,367 (2008). Its mayor is Laurids Rudebeck, a member of the Venstre (Liberal Party) political party.The main town and the site of its municipal council is the town of Tønder.