Hashim Al-Muqanna‘ (Arabic: المقنع "Hashim The Veiled", died ca. 783) was a Persian man who claimed to be a prophet. He founded an religion which was a mix of Zoroastrianism and Islam. He is viewed as a heretic by mainstream Muslims.
Al-Muqanna‘ was an ethnic Persian from Merv named Hashim ibn Hakim, originally a clothes pleater. He became a commander for Abū Muslim of Khorasan. After Abū Muslim's murder, al-Muqanna‘ claimed to be an incarnation of God, a role, he insisted, passed to him from Abū Muslim, who received it via ‘Alī from the Muhammad. Al-Muqanna‘ was reputed to wear a veil in order to cover up his beauty; however, the Abbasid Caliphate claimed that he wore it to hide his ugliness, being one-eyed and bald. His followers wore white clothes in opposition to Abbasid black. He is reputed to have engaged in magic to impress his followers as a maker of miracles.
Al-Muqanna‘ was instrumental to the formation of the Khurramiyya, a sect that claimed Abū Muslim to be the Mahdi and denied his death. When Al-Muqanna‘'s followers started raiding towns and mosques of other Muslims and looting their possessions, the Abbasids sent several commanders to crush the rebellion. Al-Muqanna‘ poisoned himself rather than surrender to the Abbasids, who set fire to his house when he was on the verge of being captured. Al-Muqanna‘ died in a fort near Kesh. After his death, the sect continued to exist until the 12th century, waiting for al-Muqanna‘ to return again.
St. Louis businessmen referenced Moore's poem in 1878 when they created the Veiled Prophet Organization and concocted a legend of Mokanna as its founder. For many years the organization put on an annual fair and parade called the "Veiled Prophet Fair," which was renamed Fair Saint Louis in 1992. The organization also gives a debutante ball each December called the Veiled Prophet Ball.
The Mystic Order of Veiled Prophets of the Enchanted Realm (founded 1889), often known as "the Grotto", a social group with membership restricted to Master Masons, and its female auxiliary, the Daughters of Mokanna (founded 1919), also take their names from Thomas Moore's poem. 
Argentine writer Jorge Luis Borges used a fictionalized al-Muqanna‘ as the central character of The Masked Dyer, Hakim of Merv, a 1934 short story, and in another story fifteen years later, The Zahir, as a past avatar of the titular object.
- The Encyclopaedia of Islam. 2nd ed. Vol. 7. Page 500.
- History, Veiled Prophet Organization, 2009, retrieved 2009-12-15
- The Grotto, MasonicDictionary.com, 2007, retrieved 2009-12-15
- Lalla Rookh Caldron, Daughters of Mokanna, Lalla Rookh Grotto, retrieved 2009-12-15