Colossus, also known as the Mummy Hamster, is a pet hamster of Nassor and one of the antagonists of the film, Frankenweenie, the others being Shelley and the Were-Rat: he is the weakest among them. When Nassor is convinced he can bring his pet hamster, Colossus, back to life with a combination of incantations and Victor Frankenstein's scientific secrets, Mummy Hamster is born! The mummy-wrapped little monster has a bigger-than-life idea of what he actually is. He later dies again when he is crushed under the gargantuan heel of Shelley.
Since the other monsters are meant to bare a resemblance to the original Universal Movie monsters, Colossus is meant to represent The Mummy. Ironically, Nassor, his owner, bares a strong resemblance to actor Boris Karloff, who not only played the Frankenstein monster from Frankenstein, but as Imhotep from The Mummy.