This book explores the ombudsman as a global institution. It has spread all over the world and its institutional development is increasingly being governed transnationally. Initially an institution of administrative law, the ombudsman has become a human rights institution and institution of good governance. These ideational shifts have influenced the global diffusion of the ombudsman but also the way in which this institution of accountability functions. The ombudsman is a peculiar institution of public accountability - both an institution and individual - that observes changes in the general political climate and engages in renegotiations of its intra-institutional position. The global models associated with the ombudsman are a source of organizational ideas, legitimacy, and sense of orientation, but they treat institutional actors differently, working also as mechanisms of inclusion and exclusion. The book tracks the global diffusion and institutional evolution of the ombudsman. Its chapters on institutional cases further explore the joint institutional history of the Parliamentary Ombudsman and the Chancellor of Justice in Finland, and the European Ombudsman.