Ghosts

A restless spirit bound either to the Spirit Realm or to an earthly place which it then haunts. Ghosts are ethereal spirits whose condition arose from a strong emotional attachment to life, perhaps strong feelings for a living person such as a lover or child. Ghosts are not often hostile towards living beings but they are generally too absorbed by their own emotions to be able to think past them.

Alchemy
Upon death in the mortal realm a ghost will leave behind ectoplasm which is a common quality alchemical ingredient.