In recent years, much research attention has shifted to the nature and implications of ‘transboundary’ crises. A crisis is traditionally defined as a shared perception of threat to a fundamental part or value of a society, which requires urgent action on the part of authorities under conditions of deep uncertainty (Rosenthal et al. 1989). We argue that a transboundary crisis compounds the previous definition, in that its origin, spread and implications unfold across borders. The transboundary crisis can, in effect, cut through multiple types of borders: geographic, policy, political, cultural, language, legal. The prototypical transboundary crises are intertwined with increasingly complex critical infrastructures and free-flowing forces linked to globalization, and would include cyber breakdowns, the spread of pandemics, and massive migration flows. Transboundary crises cast a bright spotlight on multilevel, supranational crisis governance in Europe.