The Hillebach is a small river or stream located in the German state of North Rhine-Westphalia. It is a right tributary of the Diemel, a river that eventually flows into the Weser.
The Hillebach is notable for being dammed to form the Hillebachsee (Hillebach Lake), an artificial reservoir near the town of Niedersfeld, a district of Winterberg. This lake serves as a popular recreational area, offering opportunities for swimming, fishing, and various water sports. The Hillebach originates in the Rothaar Mountains, a low mountain range in western Germany, and flows generally northwards before joining the Diemel.