Al-Qasim al-Ma'mun ibn Hammud (, died 1036) was an Arab Caliph of Córdoba in Muslim Spain for two periods, 1018 to 1021, and again for a short time in 1023 until he was driven from the city. He was the brother of the deposed Ali ibn Hammud al-Nasir. His reign was described in Ibn al-Khatib's A'mal al-a'lam. This was during a short period when the caliphate was held by the Hammudid dynasty.