Invasive Species Category 21: Non-corporeal

Center for Invasive Species Research and Assessment
Catalogue of Invasive Species Registered to Date

Category 21a: Humanoid, Non-corporial

Common names: Haunt, ghost, poltergiest, specter, spirit, spook, phantom, apparition, phantasm, shade, manes.

Subtypes

Repeaters: Non-sentient. Most common, least destructive.
A spontaneous quantum abnormality generated by a person's sudden violent death. Generally manifests on regular schedule, occasionally triggered by outside stimuli.
Movers: Limited sentience. Common, somewhat destructive.
An I.S. generated by quantum fluxuations on a macro scale catalyzed by strong emotion at time of an individual's sudden, violent death. Generally limited to moving small objects, but cases of greater strength have been recorded.
Shakers: Sentient. Uncommon, highly dangerous.
Also generated at time of individual's death, this I.S. event seems to be more connected to originating individual's sense of justice, or force of will, combined with a strong sense of unfinished purpose. A violent death is most often, though not necessarily, involved. Shakers are able to alter their appearance, and may interact on a verbal level. They are obsessed with completing their originator's unfinished task. To that end, a shaker will often seek to exert psionic control over a person.

It is, alas, chiefly the evil emotions that are able to leave their photographs on surrounding scenes and objects and whoever heard of a place haunted by a noble deed, or of beautiful and lovely ghosts revisiting the glimpses of the moon?

— Agent Algernon Blackwood