The technological advances experienced over the last years, especially those related with the emergence and extension of Artificial Intelligence and robotics, announce a new experience of reality after the fourth industrial revolution. A new context where human intelligence will coexist with other forms of artificial one generating a new landscape of risks and opportunities. Moreover, it is precisely the risk of weaponization of this technologies the focus of the present work, by understanding this phenomena as one of the biggest challenges that we face front as species. The rise of a new kind of warfare where autonomous machines will be entitled with lethal capacities being able to select, and even eliminate targets without meaningful human control it’s an scenario that doesn’t belong anymore to science fiction. A technological rise that has been creating the basis for a new arms race that can erode the fragile peace we live in. And whose first symptoms are beginning to manifest by the hand of drones, even the civilian ones as recently experienced in British airports, which can easily disrupt the activity of critical infrastructures generating chaos. Machines that even will be able to evolve into Killer Robots by performing critical tasks through the assumption of lethal capacities, whose degree of autonomy and meaningful human control are some of the key aspects that we will explore in the present book as well as its ethical and legal impacts.