Conventional theories of international relations assert that states are the primary actors possessing full sovereignty over their territories. However, the rise and prominence of non-state actors, especially violent non-state actors (VNSAs), necessitate a reevaluation of this viewpoint. VNSAs significantly shape political dynamics within the states where they operate and across the broader global landscape. A nuanced understanding of these entities enables scholars to analyse terrorist and extremist groups from a more informed perspective, facilitating a more profound comprehension of their origins, the nature of their power, and the diverse tactics they employ to achieve their objectives. This paper uses Hezbollah and Hamas as case studies to elucidate their ascendance as a prominent sociopolitical and military force. By examining their origins, ideological foundations, and strategies—including grassroots community mobilisation and their formal integration into the political system—this study illustrates the transformative potential of extremist groups as they transition into influential political actors through the lens of political opportunity structure theory, social movement theory, and constructivism. Insights from Hezbollah and Hamas’ trajectories serve as a foundational framework for understanding how such groups exploit political vacuums, leverage foreign support, and harness socio-religious grievances to consolidate power. Ultimately, this analysis sheds light on the intricate relationship between extremism and governance, offering a lens to anticipate the evolving roles of similar groups in fragile states and unstable regions.