This article considers recent developments across the western world in the lethality of lone wolf terrorists during 2016 against the contextual framework of Rapoport’s theory regarding the existence of waves of terrorism, mirroring current extreme political and social situations. It highlights the similarities in terms of world conditions coupled to modus operandi that existed during the first wave of terrorism, the Anarchist wave, and currently, while highlighting recent increased lethality. The paper illustrates that current lone wolf behaviours, and the decreasing ‘Religiosity’ of fourth wave participants indicate that the wave’s breakwater may have been reached. A discussion of the role of mental health in influencing the behaviour of ‘lone wolf’ terrorists follows. It concludes that Islamic State’s current territorial losses, coupled to increased populism across the west may be potential areas where extreme social reactionary trends occur, that will ultimately manifest themselves as ‘Fifth Wave’ Terrorism; however cautions that any predictions in this regard are extremely difficult. It recommends that policy makers and law enforcement bodies closely monitor developments amongst those reacting to these significant geo political changes; and that there is an acknowledgement that mental health considerations must be included when discussing terrorist acts, and looking at mitigation measures.