HGO may refer to: HGO Trust (formerly Hampstead Garden Opera), in London Houston Grand Opera, in Houston, Texas, United States Mercury(II) oxide (chemical symbol HgO) Héctor Germán Oesterheld (1919–1977), Argentine science fiction and comics writer, popularly known by his initials HGO Korhogo Airport in Côte d'Ivoire (IATA code HGO) Högskolan på Gotland university of Gotland, Sweden