The Opel Kadett is a small family car produced by the German automobile manufacturer Opel from 1936 until 1940 and then from 1962 until 1991, when it was succeeded by the Opel Astra.

The C-segment is the 3rd category of the European segments for passenger cars and is described as "medium cars". It is equivalent to the Euro NCAP "small family car" size class, and the compact car category in the United States.