Cassiopeian Dream Eater

Cassiopeian Dream Eaters are non-sapient alien organisms that can attach themselves to the face of a host, then trap them in a nightmare and feed off of the chemicals that are produced by the host's brain.

Anatomy
Cassiopeian Dream Eaters are jellyfish-like aliens with several long blue tentacles, and a spherical purple body with pink and white patches. When they have ensnared a victim, their purple, white and pink patches form a skull-like shape.

Powers and abilities
Cassiopeian Dream Eaters feed off chemicals that are produced by the brain during stress and thus, once they attach themselves to a host, trap them in a nightmare to feed off these chemicals. They have an incredibly tight grip on their host, and are very difficult to remove, since removing the parasite by force could rip off the host's face in the process.

Weaknesses
The Dream Eater can be removed from its host by a Galvan doctor.