Sieper Lüdenscheid GmbH & Co. KG (mostly know for its tradename Siku) is a German manufacturing company headquartered in Lüdenscheid. The company produces model cars and related products. Among the range of vehicles manufactured, the Super Series 1:55 scale plastic line is the core product, thus Siku historically could be seen as the "German Matchbox". The company also owns the well known HO scale producer Wiking-Modellbau.
Some of the products commercialised by Siku are figurines, model scale model cars, aircraft, commercial vehicles, and agricultural machinery.