This chapter introduces an idea that has enjoyed a remarkable, if hotly contested, development in the post-Cold War era: humanitarian intervention. Based on a commitment to principles of humanity and respect for life, such action seeks to alleviate the unnecessary suffering caused by violent conflict through intervening in another state, with force under limited conditions. The chapter outlines the origins of humanitarianism and the history of humanitarian intervention before discussing the shift to the responsibility to protect (R2P). As world politics becomes ever more complex, debate about global responsibilities to protect suffering strangers will continue to shape the theory and practice of international relations. While abuse of human beings has not become less widespread, the preoccupation with COVID-19 and domestic priorities meant that little consideration was given to robust action against middle powers perpetrating mass atrocities in such places as Myanmar and Tigray, let alone against major powers in Ukraine and Xinjiang.