Analyses of the humanitarian principles of humanity, neutrality, impartiality and independence often focus on the principles’ meanings and/or the challenges of applying them in practice. This article, by contrast, steps back to address foundational but somewhat neglected questions about whether these principles can accurately be designated “the” humanitarian principles; about how they came to govern the whole humanitarian sector; about their legal character and normative content; and, more fundamentally, about whether the principles can even have objective character and content. It begins by defining “humanitarian principles” and determining whether and on what basis certain principles constitute “the” humanitarian principles. The article then traces the history of how the principles came to govern the International Red Cross and Red Crescent Movement and diffused from there to non-governmental organizations and the United Nations system. It then analyzes the principles’ legal character and normative content for each of the above-mentioned categories of actor plus States, demonstrating that the principles do not – and, legally, cannot – have fixed legal character and normative content. While humanitarian actors share common understandings of the principles, legally the character and content of each principle flows from its source for the actor in question.