Today, the spread of terrorist crimes around the world requires a comprehensive definition, and international and regional documents can be used to help in this regard. After the terrorist attacks of September 11, 2001, global efforts against terrorism increased. Hence, the recognition of some terrorist acts as crimes against humanity and war crimes in international criminal law, the adoption of the Financing of Terrorism Convention, and the emergence of terrorism as a distinct international customary crime are promising developments for international prosecution of individuals who represent groups. Therefore, for the international prosecution of individuals who commit the crime of terrorism, it should be transformed into the ratification of an international treaty or the inclusion of terrorism as the fifth international crime in the Rome Statute and the expansion of the jurisdiction of the International Criminal Court (ICC). Despite the fact that the ICC does not have jurisdiction to prosecute terrorism crimes, the terrorist events of September 11, 2001, emphasized the need to include terrorist crimes as a crime within the jurisdiction of the ICC.