Since the cold war, contemporary warfare is more frequently fought between state and non-state actors. The Islamic State is a non-state actor who in a short period of time reached major achievements. Some scientists consider the Islamic State’s warfare as a developing trend of irregular warfare. Despite the Islamic State’s big achievements, it seems the organisation have not been sufficiently studied from a military science perspective. There is an obvious ambiguity in how the Islamic State should be defined. One side in the debate consider the Islamic State a revolutionary actor, the other side consider them as a hybrid one. By examining witch of McCullohs theory of hybrid warfare and Guevaras theory of revolutionary warfare most adequate can describe the Islamic State; this case study aims to increase the current understanding of the Islamic State and its warfare. The analytical result shows that the Islamic State is more adequate described as a hybrid actor. There are many similarities between the two theories, however there are some essential differences that supports the result of this paper. The use of terrorism, the relationship with the population and the use of urban terrain proves that the Islamic State is more adequate described as a hybrid actor.