Wraiths

A powerful spirit bound either to the Spirit Realm or to an earthly place which it then haunts. Wraiths are ethereal spirits whose condition arose from a great and terrible event, such as being murdered or accidentally caught inside a burning house. Wraiths are often hostile towards living beings as they feel death has unrightfully spared them while not showing the same mercy to the wraith itself.

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