The Iller is a river of Bavaria and Baden-Württemberg in Germany. It is a right tributary of the Danube, 146 kilometres (91 mi) long.
It is formed at the confluence of the rivers Breitach, Stillach and Trettach near Oberstdorf in the Allgäu region of the Alps, close to the Austrian border. From there it runs northwards, passing the towns of Sonthofen, Immenstadt, and Kempten.
