The character is based on the Star Trek captain James T. Kirk, played by William Shatner. The show's executive producer David X. Cohen has described Brannigan as "half Captain Kirk, half actual William Shatner". Zapp is voiced by Billy West, though he was originally intended to be voiced by Phil Hartman. Hartman insisted on auditioning for the role, and "of course, just nailed it" according to creator Matt Groening. However, after Hartman was murdered on May 28, 1998, West was given the role. On a Futurama DVD commentary, Groening claimed that Zapp's character and mannerisms were established in West's original audition for the character, and any similarity to Phil Hartman or his other well known cartoon characters (Lionel Hutz and Troy McClure) is simply coincidence. On the other 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."