Fischbach Castle (Luxembourgish: Schlass Fëschbech, French: Château de Fischbach, German: Schloss Fischbach) is a castle in Luxembourg. It is situated near the town of Fischbach, in central Luxembourg.
Fischbach has the longest history of any of Luxembourg's castles. The Abbey of Echternach, the wealthiest institution in Luxembourg for centuries, was the first owner of the estate of Fischbach. Records show the first liege independent of the Church took possession of the castle in 1050. The castle underwent several renovations and alterations, including complete destruction in 1635, during the Thirty Years' War.
During the second quarter of the 19th century, industrialist and metallurgist Auguste Garnier owned the castle and turned the estate into an industrial centre by constructing blast furnaces there. Grand Duke William II was the first head of state to own the castle in 1847, when he bought the estate to consolidate his political control of Luxembourg and to placate the local populace after the Belgian Revolution. He immediately ordered the demolition of Garnier's blast furnaces.
In 1884, Duke Adolphe of Nassau, who would become Grand Duke of Luxembourg when the personal union of the Netherlands and Luxembourg ended in 1890, bought Fischbach Castle from Grand Duke William III.
During the Nazi occupation of the Second World War, Fischbach served as a rest home for German artists, calling it Künstlerheim Fischbach. Despite this designation, Fischbach did not avoid the looting of art and historic artefacts that befell other palaces in Luxembourg. However, unlike the other palaces, it was not renovated or partly demolished to suit the Nazis' intentions, leaving it habitable by Grand Duchess Charlotte upon her return from exile.