'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.

Fantasms, for the most part, are normal anthropomorphic animal creatures, in several different variants- Mammalian, Avian, Insectoid, Reptilian and Aquatic, though reptilian and aquatic Fantasms are very few in number. Mammalian Fantasms look like typical mammalian creatures- dogs, cats, big cats, deer, etc.

Avian Fantasms look like differing species of birds, from hawks to ibises and owls to sparrows. Instead of having paws like a mammalian Fantasm, their wings act as their arms.

Insectoid Fantasms can range from any type of 'insect', and some non-insects like spiders. They have four or more arms, a noticeable, tail-like abdomen, large eyes with no pupils, dark-coloured sclera and light-coloured irises, and most have mandibles protruding from their jagged mouths. They have three claw-like fingers on each hand and two claw-like toes on each foot.

Reptilian Fantasms can look like any reptile, living or extinct, real or fictional.

Aquatic Fantasms look like any sort of aquatic lifeform, be it a fish or a mammal. They often have fins that resemble hands and feet.

Depending on where a Fantasm lives, there may also be some slight differences in their appearance anyway. For example, all Fantasms who reside in Moonview City have white pupils. There can also be Hybrid Fantasms, who share characterists of one or more species- such as a fox with butterfly wings, a cat with a chameleon tail and scales, or a spider-centaur!

Fantasms are made out of a dream energy that courses through them, acting as a replacement to blood. Fantasms do not bleed. Fantasms can also channel part of that energy into creating a new lifeform as a way of reproducing, and they do not need a partner to do this- just a strong will and an excess force.