Sliding Scale of Adaptation Modification

When creating a movie from a story already well-known in another medium, those making it are often faced with a crippling dilemma. How true can we stay to the source material without risking a failure at the box office? It can be a very hard call for a director. On the one hand, Fan Dumb will cry "Ruined FOREVER" should he change one iota of the source material, and he may find himself a victim of the fandom's ire from then on. On the other hand, not changing a thing can result in either a very poorly-made movie or one that relies so heavily on the source material that people unfamiliar with the work will be completely lost.

The scale runs something like this:
 * 5. Identical Adaptation: A movie in which next to nothing is changed. These rarely fare well outside the established Fandom.
 * 4. Near-Identical Adaptation: A movie that changes the material just enough to gain a PG rating or be of reasonable length. Usually rereleased with a Directors Cut.
 * 3. Pragmatic Adaptation: Probably the ideal rating. A movie that manages to capture the spirit of the original work, while at the same time, embracing the new medium. These are generally big hits.
 * 2. Recognizable Adaptation: Still bears enough resemblance to its source material that it can be realized as an adaptation.
 * 1. In Name Only: Shares only the name and possibly the main characters.

The scale, however, is not set in stone, and often times, there is overlap. Also, Tropes Are Not Bad as any movie in any of these categories can become a great success. However, the further a movie falls from the center, the less likely that is.

This trope is usually applied to movie adaptations -- The Film of the Book especially—although it can be applied to adaptations from movies as well, since other formats (books, comics, television series) have room for more material. See also The Problem with Licensed Games for the video game equivalent.

Type 5

 * Sin City
 * Black Lagoon anime
 * Mahou Sensei Negima OAV
 * The Maxx animated series
 * Rosemary's Baby
 * Doctor Who, when it's considered an adaptation
 * Many film adaptations of stage musicals; excellent examples include:
 * My Fair Lady
 * Fiddler on the Roof
 * The Phantom of the Opera
 * The 2005 version of The Producers

Type 4

 * Holes
 * The Princess Bride
 * The Lord of the Rings (Ralph Bakshi's adaptation)
 * Some of the Harry Potter films
 * Watchmen
 * Brokeback Mountain
 * Kick-Ass 
 * Fight Club
 * Fullmetal Alchemist: Brotherhood
 * The Godfather
 * The animated version of The Hobbit
 * Scott Pilgrim
 * The Little Prince (1974 film musical)
 * The Blue Bird (1976 film)

Type 3: Pragmatic Adaptation

 * Marvel's many movie franchises
 * Batman Begins and The Dark Knight
 * Batman
 * Some of the Harry Potter films
 * The Lord of the Rings (Peter Jackson's adaptations)
 * 2001
 * The Last Unicorn
 * The Novelization of Revenge of the Sith
 * The Walking Dead
 * The World God Only Knows anime
 * The first Neverending Story film
 * The first Jurassic Park movie
 * Super Dimension Fortress Macross: Do You Remember Love?
 * Sweeney Todd: The Demon Barber of Fleet Street
 * Being There
 * Charlie and The Chocolate Factory (Both the 1971 and 2005 versions)
 * Annie (Both the 1982 and 1999 versions)
 * Sonic X (Though the Sonic Adventure Series based arcs could go up to a 4)
 * The Adventures of Sonic the Hedgehog

Type 2

 * Much of the Disney Animated Canon (The Hunchback of Notre Dame and The Jungle Book especially)
 * How to Train Your Dragon
 * Dragonball Evolution
 * Dresden Files TV Series
 * Howls Moving Castle
 * Battlestar Galactica Reimagined remake
 * Cirque Du Freak based on the Saga of Darren Shan books
 * Legend of the Seeker, based of the Sword of Truth series.
 * The Shining, as directed by Stanley Kubrick
 * Fullmetal Alchemist, the 2003 anime adaptation of the manga by the same name.
 * Abridged version of Pinocchio by Phoenix Games
 * The Last Airbender
 * Batman Returns
 * Legend of the Guardians directed by Zack Snyder
 * Eragon
 * The Neverending Story 2: The Next Chapter
 * Thunderbirds (2004 movie directed by Johnathan Frakes. It visually looks like a live-action adaption of the television series, shares the same character names and usually their personalities. The movie however, changes the main disaster/rescue premise of the show to a Lighter and Fluffier, Spy Kids-esque romp. In order to support this genre change, a number of main characters from the series are also given significantly less screentime.)
 * Trigun(anime), though it occasionally goes up to three.
 * First reports from translators claim that the 2011 Live Action Adaptation of Ranma ½ starts here and may dip lower.
 * The Man Who Fell to Earth
 * Tenchi Universe, as an adaptation of the first OVA arc, although it still has the spirit of the show. Tenchi in Tokyo isn't an adaptation, but if it was, it would be somewhere between Type 1 and Type 2.
 * The Power of One movie
 * Bionicle the game and Bionicle Heroes.
 * Sonic the Hedgehog The Movie (Although it is usually considered to be a fairly good adaptation of the spirit of the games)
 * The King and I (1999 animated adaptation -- Disneyfication completely warps the storyline, but the familiar songs are still there)
 * The Wizard of Oz (1939)
 * The Secret of NIMH
 * The animated version of Return of the King

Type 1: In Name Only

 * Cheaper By the Dozen
 * Studio Ghibli's Tales From Earthsea
 * Catwoman
 * Shrek
 * The Running Man
 * Ella Enchanted
 * The League of Extraordinary Gentlemen
 * Jumper
 * Peter Benchley's Creature
 * Stuart Little
 * The Neverending Story 3: Escape From Fantasia
 * The Lost World Jurassic Park (Ironically the third movie uses more scenes from the books, despite not being based on one)
 * The Nutcracker in 3D (To both the book and ballet)
 * The Super Mario Bros movie and The Super Mario Bros Super Show
 * Bubblegum Crisis Tokyo 2040
 * Sonic Sat AM, and Sonic Underground

Special Cases

 * Simon Birch, the film adaptation of A Prayer for Owen Meany, goes from Type 1 to Type 5  as the story progresses, passing through almost every type along the way.