A stage play by Richard George that's extremely faithful to the book; Dahl approved of it.
A BBC Radio 4 adaptation (The Eighties). (Also, the novel has at least five different audiobook versions.)
A 1985 video game for the ZX Spectrum.
Roald Dahl's Willy Wonka, a 2005 U.S. stage musical created for the touring children's theatre circuit. It uses the 1971 film's songs and added new numbers by Leslie Bricusse, the film's lyricist, but is not a Screen-to-Stage Adaptation — the script is significantly different.
The 2005 film had several tie-in video games.
A 2006 Disney-style combination boat/simulator ride at the U.K. theme park Alton Towers.
In 2013, WMS Gaming introduced video slot machines based on the 1971 film!
Defictionalization: The first film adaptation was largely Merchandise-Driven. Quaker Oats gave a ton of money to the production and then changed the name of an upcoming candy line to Wonka, which is also one reason for its title change. That line initially flopped, but the brand was subsequently retooled and relaunched — it is currently owned by Nestlé. Ironically, the Wonka brand is best-known for non-chocolate products (Nerds are their most famous original creation, and their Everlasting Gobstoppers don't last forever, unfortunately), and is more popular in the U.S. than the U.K. But they do have several varieties of chocolate bars in the U.K., and Nestlé even supplied all of the edible prop candy for the 2005 film.
Now there also is an inflatable blueberry suit (obviously NSFW), to imitate Violet's transformation .
What Could Have Been: The original concept for the story didn't even have any children in it! After that, there were multiple drafts, each with different numbers of children (anywhere from five up to thirty) with different personalities and fates, as explained below. The general plot was different too: in an early draft the factory tours were a weekly event, Willy Wonka had a son called Freddie, and the story ended with Charlie getting his own chocolate shop.
Early concepts for children included Miranda Mary Piker, who was a school-obsessed swot; and Marvin Prune, who was a very conceited boy. Also — and this is absolutely true — Mike Teavee's original name was Herpes Trout. Rough draft material of the Miranda Mary Piker subplot, in which she and her father meet their comeuppance trying to destroy a machine that makes a powder that allows one to play sick for the day is featured in the book Spotty Powder and Other Splendiferous Secrets (The Missing Golden Ticket and... in the U.S.).
The Oompa-Loompas' original name was the Whipple-Scrumpets. (In the finished book, Charlie's favorite variety of Wonka Bar happens to be the Whipple-Scrumptious Fudgemallow Delight.)
Acting for TwoThousand: Every single Oompa-Loompa, even the female ones, are played by Deep Roy. Some (jackhammer, boat-rowers) are completely animatronic. Also, though some shots are recycled, minimal CGI was used - rather, Roy had to be filmed as each individual Oompa-Loompa. Don't worry, he got paid through the nose for his hard work!
Technology Marches On: Mike uses his computer to deduce the location of one of the Golden Tickets. In the 1971 film, a squad of professional programmers spend a lot of time and money to develop a massive supercomputer for this very purpose and suffer an odd A.I. Is a Crapshoot moment - see that page for details.
What Could Have Been: The Other Wiki has a history of this film's development and could-have-beens, but in addition to the facts listed there:
Michael Jackson, according to his brother Jermaine's book You Are Not Alone, was all set to campaign for the Wonka role — and then he was charged of child molestation for the second time in his career in 2003. Colleague/producer Marc Schaffel goes further with this, claiming that Michael actually wrote a whole soundtrack for the movie and submitted it to Warner Bros. back in 2000, figuring that they would give him the lead on the basis of it. But though executives loved it, they were not comfortable casting him as Willy Wonka, and offered to find another role in the film for him in exchange for the soundtrack. Michael was too dead set on the lead role to allow this. A few weeks before the movie hit theaters in July 2005, Jackson had been declared not guilty of the charges after a high-profile trial, so the unintentional, superficial resemblances between him and Depp's take on Wonka were brought up in many reviews and commentaries.
SamNeill auditioned for the role of Mr. Salt, but Burton said he wanted Johnny Depp to be the only name actor in the movie. (As for Christopher Lee's appearance, that's more Creator Thumbprint.)
Gregory Peck was first offered the role of Grandpa Joe, and he told Warner Brothers that he'd consider it. Sadly, he died before he could give his answer, but his family has revealed he was very eager to play the part. The only reason he didn't say yes right away was because he was afraid it would make him seem desperate and cause the studio to give him a lower paycheck.
The 2013 Stage Musical
Actor-Inspired Element: Willy Wonka's elegant Staff of Authority having the bendy properties of a bamboo cane (think Charlie Chaplin) was role originator Douglas Hodge's idea; he'd been rehearsing with a bamboo cane and grew used to its feel and the tricks, stances, etc. this allowed him. (See What Could Have Been below for how his input affected other aspects of the show.)
Deleted Scene / Orphaned Reference: The "Creation Overture" animated prologue was dropped in 2014 upon the first major cast turnover for reasons unknown, though pacing and/or not wanting to rerecord the narration may have been factors. This cut resulted in the loss of the Meaningful Echo of the phrase "just a bean" in "It Must Be Believed to Be Seen".
As discussed in this article, director Sam Mendes first tried to get the stage rights to the novel in the late 1980s. He tried again at the Turn of the Millennium, but the rights were with Warner Bros. by then, and they were busy with what became the 2005 film. Once that was out of the way, the go-ahead was given for a new stage adaptation in 2007. From there...
The show went through fifty drafts over a five-year period!
Before going with the conceit of adult actors in trick costumes (ala how Lord Farquaad was handled in the stage version of Shrek) to play the Oompa-Loompas, the creators considered either using puppets or casting children in the roles.
According to Douglas Hodge, "It Must Be Believed to Be Seen" was almost a Cut Song, as the songwriters came up with a far more bombastic number to take its place. That song made it to the readthrough stage, but Hodge wasn't happy with it and wanted something cheekier...so the writers, who felt much the same way by that point, played "It Must Be Believed to Be Seen" for him, and with further tweaking, the song was back in the show. Part of the tweaking involved Mr. Wonka's entrance — Hodge, who had read the book but not yet seen the 1971 movie adaptation, wanted to fake a fall as he came down the steps. Once he understood that it was too similar to the '71 film, the Internal Homage variant involving an Instant Costume Change instead of a tumble emerged.
Speaking of Hodge, he found himself choosing between playing Willy Wonka or the title character in the Cameron Mackintosh-produced revival of Barnum at Chichester Festival Theatre — not an easy decision, as he had not only expressed interest in the long-in-the-works Barnum but the two roles have many similarities. He chose Charlie and the Chocolate Factory because he'd never had the chance to take part in the creative process of staging a new musical before (of his previous roles in stage musicals, 1983's Bashville came very early in his career, and all the others were revivals).
Initially the show was set to premiere at the London Palladium, but when the West End production of Shrek The Musical announced its closing notice, leaving the similarly massive Theatre Royal Drury Lane free, plans were changed.
The Great Glass Elevator setpiece was so hard to perfect that not only were the earliest preview performances cancelled outright, but an alternative version of the "Pure Imagination" sequence was created in which the elevator is explicitly described as invisible (the actors miming its walls).