The current international humanitarian legal framework essentially categorizes people involved in armed conflicts as either combatants or civilians. However, transnational terrorist actors attack civilians as a means of belligerency thereby forcing international terrorists into one of two ill-matched categories. This article argues that terrorists are neither combatants nor civilians, suggesting that a new independent category has emerged. To correctly characterize the ever-evolving global insurgent, the international community must adopt the term "transnational belligerent." This thesis is presented in four parts. Part one defines the problem of ISIS and focuses on how terrorism has been addressed from a non-international armed conflict (NIAC) perspective. Part two discusses how current international law inadequately addresses the realities of transnational belligerents and how concepts like complementarity are expressions of how the law does not properly address this international threat. Part three surveys international approaches to defining terrorism and the historical underpinnings of belligerency. Part four analyzes the state of the law, proposes "transnational belligerency" as a necessary third category under the law, provides a model to analyze transnational belligerents, and finally proposes a means to codify the law internationally.