Red Dwarf is a British comedy franchise which primarily comprises ten series of a television science fiction sitcom that aired on BBC Two between 1988 and 1993 and from 1997 to 1999 and on Dave in 2009 and from 2012, gaining a cult following. The series was created by Rob Grant and Doug Naylor, who also wrote the first six series. The show originated from a recurring sketch, Dave Hollins: Space Cadet part of the mid-1980s BBC Radio 4 comedy show Son of Cliché, also scripted by Grant and Naylor. In addition to the television episodes, there are four bestselling novels, two pilot episodes for an American version of the show, a radio version produced for BBC Radio 7, tie-in books, magazines and other merchandise. In 2008, a three-episode production was commissioned by the digital channel Dave. These episodes were screened in April 2009 during the Easter weekend and comprised a three-part story titled Red Dwarf: Back to Earth. Unlike the majority of the original BBC episodes, this mini-series was a comedy drama filmed without a studio audience or an added laugh track. Despite the pastiche of science fiction used as a backdrop, Red Dwarf is primarily a character-driven comedy, with off-the-wall, often scatological science fiction elements used as complementary plot devices. In the early episodes, a recurring source of comedy was the "Odd Couple"-style relationship between the two central characters of the show, who have an intense dislike for each other and are trapped together deep in space. The main characters are Dave Lister, the last known human alive, and Arnold Rimmer, a hologram of Lister's dead bunkmate. The other regular characters are Cat, a lifeform which evolved from the descendants of Lister's pregnant pet cat Frankenstein, Holly, Red Dwarf's computer, Kryten, a service mechanoid, and, as of Series VII to Back to Earth, Kristine Kochanski, an alternative-reality version of Lister's long-lost love.