This chapter focuses on three EU agencies: the European Agency for Law Enforcement Training (CEPOL), the European Agency for the Operational Management of Large-Scale Information Systems (EU-LISA), and the European Cyber Security Agency (ENISA). This chapter analyses their origin, structure, delegation of powers, and main activities. CEPOL specializes in the education and training of law enforcement personnel, EU-LISA manages extensive information systems in the area of justice and home affairs, and ENISA focuses on cyber security. This chapter highlights the common features of these agencies, such as their role in ensuring EU security, cooperation between agencies and Member States and their contribution to the European security architecture. Key takeaways include the importance of these agencies to the effective functioning of the EU, their role in responding to security challenges such as the Russian invasion of Ukraine, and their contribution to the protection of European citizens.