Organizations
- Croatian Defence Council (Hrvatsko vijeće obrane or HVO in Croatian), a military formation of the self-proclaimed Croatian Republic of Herzeg-Bosnia during the Bosnian War
- Hawaiian Volcano Observatory, a unit of the US Geological Survey
- Health Volunteers Overseas, a Washington, DC-based nonprofit organization
- Hidden Valley Observatory, an astronomical observatory located just outside of Rapid City, South Dakota
- Hindu Volunteers' Organisation
Read more about this topic: HVO