BETA XII-A ENTITY

Planet of Origin: unknown, but first encountered in the Beta XII-A system.

The Beta XII-A entity is a parasitic noncorporeal being composed of pure energy. The entity appeares as a small, circular pattern of multiple swirling lights in different colors, although it becomes red in hue and emitts a high-pitched wail when "feeding". It feeds on the emotions of hatred, anger, and primitive predatory instincts exhibited by sentient organic beings in close proximity to it. If those emotions are not present, the entity will try to spawn such feelings. It controls the instantaneous transmutation of matter from one form to another, can pass through solid objects at will, teleport from one location to the next, and influence the thoughts of others. It could heal an organic being's mortal wounds, and could even alter a person's memories. The entity appears unable to communicate in any fashion understandable to organic beings. Although its motives and nature are not wholly known, it lacks the same ethical standards of most humanoids and largely acts in a malignant fashion. Its only weakness appears to be exposure to emotions of humor, good nature, and friendship; it is particularly susceptible to laughter.
It shares several traits with the redjac entity.

Source: Star Trek universe, (TOS: "Day of the Dove")