The European Council is one, if not the, key institution of the European Union (EU). Coming together for the first time about 50 years ago, in March 1975, the European Council comprises notably the Heads of State or Government of the EU member states, thus linking national and European levels. It takes important decisions in various policy areas and has regularly expanded the EU’s agenda and competences. In recent years, the European Council has acted as the prime crisis manager. At the same time, because of its requirement for consensus and its own small internal capacities, it is vulnerable to blockades and depends on other EU institutions for the preparation and implementation of its decisions. This article analyzes the European Council as key actor in the EU’s multi-level and multi-institutional system of governance. Comparing and bringing together different theoretical perspectives, it critically examines its various roles, functions, and shortcomings. Contrary to the predominant view, the European Council – despite its intergovernmental composition – tends to strengthen the EU’s supranational procedures. With this institution becoming ever more important and visible, the paper also suggests avenues for the further study of the European Council.