The Ghost Nebula was a nebula and a sector in the Expansion Region that blocked light from most of the stars beyond and within it, isolating it from the galaxy and inspiring its name. Ultraviolet radiation from massive stars at its center ionized the surrounding gases to form plasma, which bathed the planets within the nebula in their ultraviolet light. It surrounded the inhabited planets of Umbara and Atoa, respective homeworlds of the near-Humans Umbaran and Atoan peoples.
During the Clone Wars the nebula was considered a vital (though isolated) supply route, and the Galactic Republic fought against the Confederate-aligned Umbaran militia for control of their homeworld. After the creation of the Galactic Empire, the Atoan system was conquered after a failed rebellion led by the traitorous Garoche Tarkin and local insurgents.
- Star Wars: The Clone Wars – "Darkness on Umbara" (Mentioned only)
- Star Wars: Darth Vader and the Lost Command (First appearance)
- Dark Times—Fire Carrier 1 (Mentioned only)
- Star Wars: Attack of the Clones The Visual Dictionary (First mentioned)
- Ultimate Alien Anthology
- The New Essential Guide to Alien Species
- "Strangers Among Us: The Aliens Who Built the Galactic Empire"—Star Wars Insider 96
- Galaxy of Intrigue
- The Essential Atlas