A.K.A.: Id, The Monster from the Id, The Subconscious Monster

Height: can change size at will (tends to be 20 feet tall or so)

Weight: A lot

Regular Abilities: big claws on feet, big teeth, immense strength

Special Abilities: can render itself invisible, can regenerate it’s matter instantaneously, can heat up objects

Weakness: will temporarily disappear if the subconscious mind is distracted, destroyed if the person fathoming it is killed

Film Appearances: Forbidden Planet (1956)

History: an expedition is sent to the planet Altair (in the Aquilae constellation) to assess the situation of a research colony that came to the planet over 19 years earlier. After traveling over a year with hyperdrive travel the 17 light years to get there, the expedition finds that only one scientist and his daughter are the only one’s remaining. The reason is that an advanced civilization called the Krell invented a powerful energy reactor to eliminate all need for physical instrumentation, but were wiped out when their id (subconscious mind) produced monsters with the rational of the primitive mind. The scientist himself was able to utilize the technology to increase his brainpower, but the side effect was that he created a monster of his own. After his efforts to ward off the expedition team through fear failed, he was eventually convinced by his daughter and the commander of the expedition to stop the monster and destroy the machine.

Since this "monster" is a physical projection of the subconscious mind that is powered by an advanced alien device with nearly infinite amount of energy, the creature can regenerate itself constantly and thus repair any damage to itself the instant that damage is received (such as from energy fences and blaster fire). Essentially the thing is invincible, unstoppable, and capable of anything that it wishes to be capable of. The only way to stop it is to eliminate the source.