Nibbler is Leela's pet Nibblonian, whom she rescued from an imploding planet and adopted early in the series. While the size of an average housecat, his race is capable of devouring much larger animals and excretes dark matter, which until Bender's Game is used as fuel for space cruisers in the series. Despite his deceptively cute exterior, Nibbler is actually a highly intelligent superbeing whose race is responsible for maintaining order in the universe. He is revealed in "The Why of Fry" to have been directly responsible for Fry's cryogenic freezing.