Qalaat Najm is a castle located on the right bank of the Euphrates, near the town of Manbij in Aleppo Governorate, Syria. The castle probably stood on the site of an earlier Roman site and is known from Arabic texts since the 7th century AD. Reconstruction works were carried out in the castle by Nur ad-Din Zangi and Az-Zahir Ghazi during the 12th and early 13th centuries.