There have been multiple professional and amateur stage adaptations of The Hitchhiker's Guide to the Galaxy. There were three early professional productions, which were staged in 1979 and 1980.
The first of these was performed at the Institute of Contemporary Arts in London, between 1 and 19 May 1979, starring Chris Langham as Arthur Dent (Langham later returned to Hitchhiker's as Prak in the final episode of 2004's Tertiary Phase) and Richard Hope as Ford Prefect. This show was adapted from the first series' scripts and was directed by Ken Campbell, who went on to perform a character in the final episode of the second radio series. The show ran 90 minutes, but had an audience limited to eighty people per night. Actors performed on a variety of ledges and platforms, and the audience was pushed around in a hovercar, 1/2000th of an inch above the floor. This was the first time that Zaphod was represented by having two actors in one large costume. The narration of "The Book" was split between two usherettes, an adaptation that has appeared in no other version of H2G2. One of these usherettes, Cindy Oswin, went on to voice Trillian for the LP adaptation.
The second stage show was performed throughout Wales between 15 January and 23 February 1980. This was a production of Clwyd Theatr Cymru, and was directed by Jonathan Petherbridge. The company performed adaptations of complete radio episodes, at times doing two episodes in a night, and at other times doing all six episodes of the first series in single three-hour sessions. This adaptation was performed again at the Oxford Playhouse in December 1981, Plymouth's Theatre Royal in May–June 1982, and also at the Belgrade Theatre, Coventry, in July 1983.
The third and least successful stage show was held at the Rainbow Theatre in London, in July 1980. This was the second production directed by Ken Campbell. The Rainbow Theatre had been adapted for stagings of rock operas in the 1970s, and both reference books mentioned in footnotes indicate that this, coupled with incidental music throughout the performance, caused some reviewers to label it as a "musical". This was the first adaptation for which Adams wrote the "Dish of the Day" sequence. The production ran for over three hours, and was widely panned for this, as well as for the music, laser effects, and the acting. Despite attempts to shorten the script, and make other changes, it closed three or four weeks early (accounts differ), and lost a lot of money. Despite the bad reviews, there were at least two stand-out performances: Michael Cule and David Learner both went on from this production to appearances in the TV adaptation.
In December 2011 a new stage production was announced to begin touring in June 2012. This included members of the original radio and TV casts such as Simon Jones, Geoff McGivern, Susan Sheridan, Mark Wing-Davey and Stephen Moore with VIP guests playing the role of the book. It was produced in the form of a radio show which could be downloaded when the tour was completed. This production was based on the first four Fits in the first act, with the second act covering material from the rest of the series. The show also featured, a band, who performed the songs Share and Enjoy, the Krikkit song Under the Ink Black Sky, Marvin's song How I Hate The Night, and Marvin, which was a minor hit in 1981.