NSU Motorenwerke AG, normally just NSU, was a German manufacturer of automobiles, motorcycles and pedal cycles, founded in 1873. It was acquired by Volkswagen Group in 1969. VW merged the company with Auto Union, to eventually evolve into Audi as it is known today.

NSU began as a knitting machine manufacturer in the town of Riedlingen on the Danube in 1873, and moved to Neckarsulm, where the river Sulm flows into the Neckar, in 1884. In 1886 the company began to produce bicycles, the first of them branded as the "Germania", and by 1892, bicycle manufacturing had completely replaced knitting machine production. At about this time, the name NSU (from Neckar and Sulm) appeared as a brand name.

The first NSU motorcycle appeared in 1901, followed by the first NSU car in 1905. In 1932, the car factory in Heilbronn was sold to Fiat.

During World War II NSU designed and produced the Kettenkrad, the NSU HK101, a half-tracked motorcycle with the engine of the Opel Olympia.

In December 1946 Das Auto reported the company had resumed the manufacture of bicycles and motor-bicycles at Neckarsulm. For Germany this was a time of new beginnings: in July 1946, a new board had been appointed, headed up by General Director Walter Egon Niegtsch, who earlier in his career had spent 17 years with Opel.