The toppling of Saddam Husayn and his Iraqi Ba‘th Party government led to a series of profound political and social changes both inside and outside of Iraq. The most significant of these changes was a new sense of social and political empowerment for the country’s Shi‘i Muslims, who underwent a major revival. Shi‘i politicians rose to key positions of power in the new government and a reopening of Shi‘i religious institutions, such as the seminaries in cities such as Najaf and Karbala, and the public performance of Shi‘i religious rituals, such as the annual ‘Ashura processions, long banned by Saddam. The door was also opened for the public emergence of relatively small yet disproportionately influential, millenarian (“Mahdist”) groups among the Iraqi Shi‘a. These movements exist within the larger, complex Iraqi Shi‘i social milieu and can only be fully understand as products of the environment of widespread insecurity, unrest, and violence that followed the overthrow of the Iraqi Ba‘th Party. The paper traces the development and evolution of the contemporary millenarian trend within Iraqi Shi‘ism, with a focus on the Sadr Movement, the Ansar al-Hasani led by Mahmoud Sarkhi al-Hasani, the cultish group of Ahmad al-Hasan “al-Yamani,” and the Soldiers of Heaven, an apocalyptic cult that allegedly plotted to assassinate the grand ayatollahs of Najaf in 2007. The paper makes two central arguments. First, the Shi‘i textual tradition regarding the twelfth Imam, who is believed by Shi‘is to be in a mystical occultation or hiding until an appointed time when he will return, will likely prevent Mahdist groups from becoming widespread. Senior Shi‘i ‘ulama (religious scholars), including the grand ayatollahs of Najaf, have delivered pointed critiques of these movements and the populist millenarian sentiments that they seek to stoke. Second, despite frequent comparisons between these groups, significant ideological, social, and political differences exist between these movements. All five movements, despite their important differences, can only be fully understood as products of the environment of widespread violence and insecurity that followed the overthrow of Saddam’s regime. The paper will be will based on a careful analysis of written and visual primary sources produced by Iraqi millenarian Shi‘i movements.