The ESO-Athena synergy exercise ends with the publication of the ESO-Athena Synergy White Paper. In this work, the ESO-Athena Synergy Team highlights the many synergies between Athena and the ESO facilities, current and future, covering the following Athena key scientific objectives:
• The Hot Universe: Early groups and clusters and their evolution, Physics of the Intracluster medium, Missing baryons in cosmic filaments;
• The Energetic Universe: Supermassive black hole (SMBH) history, SMBH accretion disks, Active Galactic Nuclei feedback -- Molecular outflows, Ultra-fast outflows --, Accretion Physics, Transient Science;
• Observatory Science: Star Formation, Stars.