Saaleck Castle is a hill castle near Bad Kösen, now a part of Naumburg, Saxony-Anhalt, Germany.
In 1922, two of the men who had killed Walther Rathenau, the foreign minister of Germany, hid at Saaleck Castle but were tracked down by the police. The Nazi regime later put up a memorial plaque at the castle and turned their grave in Saaleck cemetery into a heroes' shrine.
The castle is now mostly ruined, but its two towers feature small exhibits and it is a popular tourist attraction. Saaleck Castle is a stop on the designated tourist route Straße der Romanik.