Gengenbach (German pronunciation: [ˈɡɛŋənˌbax] (listen); Low Alemannic: Gängäbach) is a town in the district of Ortenau, Baden-Württemberg, Germany, and a popular tourist destination on the western edge of the Black Forest, with about 11,000 inhabitants. Gengenbach is well known for its traditional Alemannic "fasnacht", ("Fasend"), a kind of historically influenced celebration of carnival, where tradition is followed, from wearing costumes with carved wooden masks to clapping with a "Ratsche" (a traditional-classic wooden "sound-producing" toy). Gengenbach also boasts a picturesque, traditional, medieval town centre ("Altstadt"). The traditional town Gengenbach is the proud owner of the world's biggest advent calendar. The 24 windows of the 18th century town hall represent the 24 "windows" of an Advent calendar. The town also hosts a department of The Graduate School of Offenburg University of Applied Sciences, part of the University of Applied Sciences Offenburg. The nearest cities in the region are Offenburg, Freiburg, Karlsruhe, Baden-Baden and Strasbourg/France. Gengenbach is twinned with the town of Obernai, Alsace, France.

In the 2005 film version of Charlie and the Chocolate Factory, Gengenbach was inaccurately referred to as Düsseldorf, the place where the character Augustus Gloop becomes the first finder of Wonka's Golden ticket.