Between the eighth and tenth centuries, Muslim caliphs deemed rebellions against their rule as the work of Satan. In the Umayyad (661-750 C.E.) and Abbasid eras (750-1256), several government letters referred to any group who challenged caliphal authority as awliyā ʾ Iblīs (friends of the Devil). Government officials adapted qurʾānic conceptions of the Devil to legitimize the caliphs’ authority as God’s deputies. However, this political-religious conception of the Devil has continuity with the political theology of late antique Christian Roman emperors who used similar language for those who threatened their rule. In this talk, I trace this genealogy of the Devil and his supposed human allies as the caliphate’s archenemies in government letters written for the Umayyad caliphs Hishām b. ʿAbd al-Malik, and Marwān II (r. 744-750), and the Abbasid caliphs, al-Maʾmūn’s (r. 813-833), and al-Radī’ (r. 934–40). By closely examining these official letters, I will reveal in this talk how understanding this political framing of the Devil offers us key insight into the tense construction of early Islamic sovereignty.