Al-Qasim al-Ma'mun

Al-Qasim al-Ma'mun ibn Hammud (, died 1036) was the 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.

Brother of the Caliph Ali ibn Hammud al-Nasir, al-Qasim claimed the throne on 28 March 1018 shortly after his brother's assassination. His reign is described in Ibn al-Khatib's A'mal al-a'lam.

At the outset of al-Qasim's reign, Umayyad loyalists who had been plotting to overthrow his brother convinced the a grandson of Abd al-Rahman III, Abd al-Rahman ibn Muhammad ibn Abd al-Malik, to claim the throne. On 29 April 1018, the conspirators proclaimed Abd al-Rahman IV caliph. Shortly thereafter he was killed in a campaign to capture Córdoba.

His nephew, Yahya ibn Ali, refused to recognize his reign. With Berber supporters, he marched on Cordoba in August 1021 to seize the throne. al-Qasim abandoned the city and fled to Seville. Yahya entered Cordoba and was proclaimed caliph on 13 August 1021. His reign lasted only a year and a half before the citizens of Cordoba forced him to flee. Al-Qasim then returned and retook the throne on 6 February 1023. The citizens of Cordoba, however, have had enough of Hammudid rule and six months later riots forced al-Qasim to flee the city again, this time seeking refuge in Jerez. He was found and imprisoned by Yahya, who later had him assassinated.