Al-Mustamsik (Arabic: المستمسك بالله; died 1521) was the sixteenth and penultimate Abbasid caliph of Cairo under the tutelage of the Mamluk Sultanate. He served as caliph twice, his first term from 1497 to 1508 and his second term from 1516 to 1517, when he abdicated the position to his son, al-Mutawakkil III.

• "Biography of Al-Mustamsik" (in Arabic). Islampedia.com. Archived from the original on 2008-06-11.

• Garcin, Jean-Claude (1967). "Histoire, opposition, politique et piétisme traditionaliste dans le Ḥusn al Muḥādarat de Suyûti" [History, opposition, politics and traditionalistic pietism in Suyuti's Ḥusn al Muḥādarat] (PDF). Annales Islamologiques (in French). 7. Institut Français d'Archéologie Orientale: 33–90. doi:10.3406/anisl.1967.909. S2CID 259055409. Archived from the original (PDF, 14.62 MB) on 2011-07-24. Retrieved 2010-07-22.
• Holt, P. M. (1984). "Some Observations on the 'Abbāsid Caliphate of Cairo". Bulletin of the School of Oriental and African Studies. 47 (3). University of London: 501–507. doi:10.1017/S0041977X00113710. JSTOR 618882. S2CID 161092185.