In his short story The Stolen Body, Wells has written about evil spirits that float in an astral world that has no sound, parallel but distinct from our own. Spirits take form of clouds and vapors that resemble terrifying faces. They are capricious and vehement by nature. They viciously envy and thirst for existence that's been denied from them.
Powers/Abilities[]
In proper circumstances they might be able to possess a human body that has had it's spirit travel too far into astral plane. They don't understand life, and given chance to taste it they may become reckless and act violently, gathering as many sensations as possible in their time of possession, which apparently might be permanent unless a knowledgeable medium guides original human spirit back to its body.
It's suggested if human spirit does not return to it's body before mortal shell expires, it becomes forever trapped inside the silent astral world of leering faces.
Weaknesses[]
It is questionable if these evil spirits are intelligent in the way humans perceive intelligence. They're attracted to existence and given taste of it they try to experience it to the fullest, but it seems likely they cannot act rationally while possessing a human body to prolong their time on Earth. They don't also seem to oppose medium's guidance in aggressive manner.