Existing typologies of the European administrative space locate decision‐making powers with the European Commission, member state governments, and EU and national agencies, sometimes aided through regulatory networks. This article argues that those typologies are incomplete because they do not take into account the existence of transnational executive bodies. These are public authorities that are responsible for administering and implementing EU policies across multiple member states, that are part of neither domestic nor EU institutions and whose decisions are legally binding. They represent a potentially highly prevalent form of governance in a previously uncharted area of the European administrative space. We document their workings by presenting a case study of the Rhine‐Alpine Corridor organization, a transnational executive body implementing parts of the EU rail freight policy.