The European Southern Observatory is an astronomical research organisation.
ESO may also refer to: Employee stock option (also: executive stock option) Ether Saga Odyssey, a fantasy massively multiplayer online role-playing game The Elder Scrolls Online, a fantasy massively multiplayer online role-playing game Existential second-order logic ESO (motorcycles) Eso (town), Orhionmwon, Edo State, Nigeria
Organisations European Standardisation Organisations: CEN (European Committee for Standardization), CENELEC (European Committee for Electrotechnical Standardisation) and ETSI (European Telecommunications Standards Institute) Ensemble Studios Online Edmonton Symphony Orchestra Energijos skirstymo operatorius (ESO), Lithuanian electricity transmission network operator Evergreen Symphony Orchestra, an orchestra in Taiwan Eteläsuomalainen osakunta, a student nation at the University of Helsinki Libyan External Security Organisation External Security Organisation, the Ugandan external secret service École secondaire d'Oka, a public high school in Oka, Quebec, Canada National Grid Electricity System Operator (ESO), British electricity transmission network operator
Music English Symphony Orchestra and English String Orchestra, two related classical orchestral ensembles Eso-Charis, Christian metal band (and self-titled album) Bliss n Eso, Australian hip hop group
See also Esō, also known as Hyechong, a Korean priest who transmitted Buddhism to Japan