The fall of Iraq's Baath regime was swiftly followed by the proliferation of terrorist groups, militant organisations and an ongoing sectarian conflict that continues to engulf the region. However the Shia militias involved remain poorly understood. Referred to variously as Iranian proxies, Iraqi nationalists, state-builders and terrorists, they have emerged from the ruins of post-2003 Iraq to acquire considerable power. These militias are multifarious in nature--they overlap and interact with the state and social actors, including Iranian proxies but also groups vehemently opposed to Iran's interference in Iraq's affairs. And the challenge of engaging them is compounded by war in Syria, where such groups have shifted the balance of power in the regime's favour, under Iranian supervision. Indeed Iran has exploited instability across the region to establish, empower, and entrench its proxy organisations as it attempts to shape the future of the region. Shia militias will shape the future of Iraq (and the region) but to what extent will they do so, and can they be stopped? Sacred Warriors draws on the author's decade-long research on Iraq's Shia community and fieldwork in Baghdad, Najaf and Karbala to inform the debate