hand, in an interview for the website TV Squad, Billy West states that his Zapp Brannigan is an imitation of Hartman and also "modeled after a couple of big dumb announcers I knew." During a live event, West stated that he partially modelled Brannigan's cadence after the radio persona of Doug Tracht, also known as "The Greaseman." Kif Kroker Lieutenant Kif Kroker (voiced by Maurice LaMarche) is the long-suffering assistant to Captain Zapp Brannigan, and Fourth Lieutenant on the Democratic Order of Planets (DOOP) starship Nimbus. Kif is a short and thin green-skinned alien from the planet Amphibios 9. His frustration with Brannigan's arrogance, general incompetence, and lack of personal boundaries in Season 1 leads him to be a disaffected, indifferent, sardonic lackey, although his personality develops through the course of the series, becoming more emotional, tender and sweet-natured later on. Zapp thinks Kif to be his best friend and loyal confidant, whereas Kif sees Brannigan as an incompetent and vain buffoon, going so far as to call him a jackass in "Love's Labours Lost in Space". Despite this, Kif seemingly has some loyalty to Brannigan, even continuing to associate with him after Brannigan caused him to be court-martialed along with him in "Brannigan, Begin Again". Kif is in a relationship with Amy Wong, and he compares his body plan to a sea cucumber. Nibbler Lord Nibbler (voiced by Frank Welker) masquerades as an innocent, cute and unintelligent pet during most of the series. In reality, he is a highly intelligent Nibblonian and capable of communication, but tries to avoid suspicion while he protects the Earth in general and Fry in particular from the Brainspawn. As with all Nibblonians, Nibbler's feces consist of dark matter, which can be used as starship fuel. It is an extremely dense material, "each pound of which weighs over ten thousand pounds," according to Professor Farnsworth in the season 1 episode, "Love's Labours Lost in Space." After he accidentally reveals to the Planet Express crew that he can speak in Bender's Big Score, he forgets to wipe their memory of his intelligence, which it turns out does not affect them much, and from then on he speaks freely to the crew. In the pilot episode, Nibbler's shadow can be seen as Fry falls into the cryogenic freezer, alluding to the reveal in the fourth season episode "The Why of Fry" that he helped send Fry