Ghost World or called by the Turtles and the Foot Clan as Netherworld is a dimension that inhabited by all kinds of the Ghosts.
- Kiyomi Haunterly
- Grim Reaper
- River Styxx
- Students of Monster High
- The Kraang are interesting and also want to colonize this dimension as well. But Dimension X and the Ghost World didn't have much connection like the Earth has.
- At the Grand Central Station between Dimensions of the Kraang, if they got lucky, one of their portals can be accidentally open to the Ghost World.
- Ironically, the ruler of this world is not the ghostly being.
- It is seemingly that the Demodragons are ruling-calss people of the Ghost World.