5 key points: While mercenaries were used across many civilizations they were not a dominant fixture of modern war until their reemergence in the past couple decades under the label private military companies (PMCs) Links to an external site.. The industry is far from saturated, with at least one market report Links to an external site. anticipating a 7.4% growth rate until it becomes a $457.5 billion dollar industry by 2030. This represents a whole new form of the military industrial complex, no longer just military research, software, and hardware. But PMCs also raise serious questions about accountability and global security when a variety of governments, as well as companies and wealthy families can hire groups offering combat capabilities. Here is a partial Wiki list of such firms: https://en.wikipedia.org/wiki/List_of_private_military_contractors