'Fantasms' is the collective name for the inhabitants of both Fantasium and its surrounding alternate worlds- Neo-Fantasium and Pathopeir. Typically, a Fantasm is an anthropomorphic animal of varying species and types. Most appear mammalian or avian, some insectoid, and rarely do Fantasms appear as reptilian or aquatic species. However, this does not mean that they do not happen.

Fantasms can inhabit any of the four major areas of Fantasium- Moonview City, Sanctum, Bastion and Carnival-however, they can also exist outside of those areas- whether that be the frigid lands north of Haven and Sanctum, to the deserted Moonview Manor Island, to the Forlorn Cove to the west of Carnival. They can be found in even the least habitable corners of Fantasium.
Fantasms cannot exist in Somnius, at least for prolonged periods of time.