"Futurama" had eight main cast members. Billy West performed the voices of Philip J. Fry, Professor Farnsworth, Doctor Zoidberg, Zapp Brannigan, and many other incidental characters. West auditioned for "just about every part", landing the roles of the Professor and Doctor Zoidberg. Although West read for Fry, his friend Charlie Schlatter was initially given the role of Fry. Due to a casting change, West was called back to audition again and was given the role. West claims that the voice of Fry is deliberately modeled on his own, so as to make it difficult for another person to replicate the voice. Doctor Zoidberg's voice was based on Lou Jacobi and George Jessel. The character of Zapp Brannigan was originally created and intended to be performed by Phil Hartman. Hartman insisted on auditioning for the role, and "just nailed it" according to Groening. Due to Hartman's death, West was given the role. West states that his version of Zapp Brannigan was an imitation of Hartman and also "modeled after a couple of big dumb announcers I knew".