The monster resides in Calvin's closet, lying in wait to eat him. The Freak is not clearly seen, yet some of its features can be surmised from glimpses of the beast:
Firstly, it is of considerable size, with a mouth able to contain children even when closed to digest them. Secondly, it appears to be bipedal and even somewhat humanoid. Its limbs are not seen, but the creature is stated as tentacled. It bears claws, but these are of questionable necessity as it employs the multifarious suckers on its tentacles in order to grab its prey. The large spikes on its backside and green, dragonlike tail are also unexplained. Its eyes, perched atop stalks, are a threatening shade of red.
The monster must be afraid of Hobbes, as the latter managed to chase him away while half-asleep.