Current challenges are truly global, ranging from climate change to territorial conquests, increasing vulnerability of cyberspace, and economic inequality. The concept of unity underlies the core logic of the discipline but is frequently taken for granted. For instance, Article 1 of the UN Charter mentions ideals such as co-operation of nations in attaining universal peace and harmonizing their actions with the aim of achieving shared objectives. The Rome Statute of the International Criminal Court also makes it clear that the fight against impunity for the most serious crimes concerning humanity as a whole is a universally shared task (emphasis added). This meta-level thinking is, however, often overshadowed by a zero-sum logic with clear 'winners' and 'losers'. This edited collection invites a U-turn in this line of argument by treating unity not as an abstract cosmopolitan idea, but rather as a pre-condition for the continued co-existence and prosperity of people around the world. Thus, the core assumption of the volume is that there exists one global community – humankind – benefitting from the protection of international criminal law. Stoic philosophy inspires this foundational thought. This very same humankind, then, is also the bearer of risks and harms, if examined from the intergenerational point of view. This edited collection focuses on the idea of 'unity' as the central protected legal interest in international (criminal) law. It offers perspectives from leading scholars and practitioners in the field of international criminal justice. This discussion is very timely given the diverse and increasingly inter-related nature of threats to humanity. It is no coincidence that the word 'unity' is an integral part of the word 'humanity'.