Wisp

Wisps are the beings that animate the hollow men, they are the ancient ghosts attached to the weave itself.
When a citizen of Albion dies with strong emotional attachments to the world, such as a guilty conscience or important matters left unresolved, they become a ghost instead of moving on. Ghosts are able to freely transform into a Wisp
Over time the human part of a ghost will dissolve into nothing, if their ties to the world are not resolved, leaving only a restless spirit in its place known as a Wisp. These Wisps harbour anger, likely resulting from jealousy towards the living citizens of Albion and animate the bones of the deceased in order to take this anger out physically.
Hollow Men serve as a host body for the Wisps to exemplify their rage towards the living and upon destroying the Hollow Men, the Wisps leave the body. It is currently unknown if the Wisps are also destroyed along with the body or if they just return to being Wisps.
Wizards are known for becoming wisps, despite being happy in life.