Frontex (from French: Frontières extérieures for "external borders", legally: European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union) is the European Union agency for external border security. It is responsible for co-ordinating the activities of the national border guards in ensuring the security of the EU's borders with non-member states. Frontex is headquartered in Warsaw, Poland.

Frontex was established by Council Regulation (EC) 2007/2004. The agency started to be operational on October 3, 2005 and was the first EU agency to be based in one of the new EU states—from 2004.

Frontex' mission is to help EU Member States implement EU rules on external border controls and to coordinate operational cooperation between Member States in the field of external border management. While it remains the task of each member state to control its own borders, the Agency is vested with the function to ensure that they all do so with the same high standard of efficiency.