Mustafa al-Siba'i (Arabic: مُصطَفى السِّبَاعِي, romanized: Muṣṭafā as-Sibāʿī) was a Syrian politician and activist. He was dean of the Faculty of Islamic Jurisprudence and the School of Law at the University of Damascus. From 1945 to 1961 he was the leader of the Muslim Brotherhood in Syria, the Syrian branch of the Muslim Brotherhood.