Scharzfels Castle is the medieval ruin of a fortification located east of the village of Scharzfeld in the borough of Herzberg am Harz in central Germany. It lies in a wood on a ridge about 150 m above the Oder valley. For centuries after its construction in the 10th or 11th century it remained an impregnable fortress. The inner ward is built on a dolomite rock outcrop about 20 m high. The castle was first captured after a siege in 1761 during the Seven Years' War and then blown up.

Sophia Dorothea of Brunswick-Lüneburg-Celle was the repudiated wife of future King George I of Great Britain. The union with George, her first cousin, was a marriage of state, arranged by her father George William, her father-in-law the Elector of Hanover, and her mother-in-law, Electress Sophia of Hanover, first cousin of King Charles II of England. Sophia Dorothea is best remembered for her alleged affair with Count Philip Christoph von Königsmarck that led to her being imprisoned in the Castle of Ahlden for the last thirty years of her life.