According to the traditional theory of international law, states play a primary role in the creation of international law. The factual situation in the international community points to the need for new approaches that will take into account other non-state actors and give them a role in the creation of international law. The core thesis of this master thesis is that there is an urgent need and a real possibility of involving non-state armed groups in the procedures of creating norms of international humanitarian law in non-international armed conflicts. The first part of the paper presents the theoretical possibility of a departure from the traditional theory, which gives countries the primary and exclusive role in the creation of international law. The category of non-state actors is extensive and diverse, and therefore, it is not possible to apply a uniform approach for all. The categorization of different types of non-state actors is being addressed below, since the distinction within the group itself is necessary in order to adapt the role in the creation of international legal norms. Different approaches to the recognition of the role in the creation of international law have been presented, from completely excluding approaches, that recognize this role exclusively to the states, to approaches that include other subjects of international law. Today, most of the armed conflicts are non-international, therefore the fact of the increasingly important role of armed groups can no longer be overlooked. In the second part of the thesis the specific need and the actual possibility of involving non-state armed groups in the creation of norms of international humanitarian law in non-international armed conflicts is being discussed, as well as the related advantages and challenges. Finally, the concrete possibilities of involving armed groups in the creation of international norms are presented, by recognizing unilateral acts issued by armed groups, concluding bilateral agreements and accession to multilateral international treaties and consideration of the conduct of non-state armed groups in the creation of customary international law.