There have been hundreds, maybe even thousands of films based on novels. Usually when a film is adapted from a novel, the writers and directors take some liberty when it comes to book accuracy. This can be due to time constraints, difference in interpretation, or simply wanting to change things up.
A frequent thing that happens when adapting novels to the big screen is toning them down or making them more accessible to a wide audience. This is likely because movie audiences often expect a happy ending or simply want to have a good time at the cinema. There are numerous novels that are much darker than their film counterparts, and hopefully, they can one day be adapted more faithfully.
5 Jaws
Jaws is often considered Hollywood's first ever blockbuster. Steven Spielberg's shark thriller masterpiece has been adored by audiences worldwide for decades. Some may not know it was actually adapted from a novel by Peter Benchley. There were many changes made when adapting the novel, most of them actually toned down some of the darker aspects of the novel.
One important change was removing the racist and homophobic undertones the book contained. Another change was made to how likable the characters are. The protagonists in the book are almost written so that the reader wants them to be eaten by the shark. Much different than the relatable family man Brody shown in the film. Lastly, the books ending is much darker. Hooper and Quint both fall victim to the shark and Brody is left stranded alone at sea.
4 American Psycho
When American Psycho first released in theaters it was met with some controversy due to its violence and dark subject matter. Surprisingly the film was actually much less dark than the book is. The book goes into extreme detailed on how Patrick Bateman kills his victims and why. This includes graphic descriptions of violence for every person he kills, not to mention he kills twice as many people in the book than in the movie.
The movie's violence is not uncommon for most horror movies while the book was so violent it got banned in many countries. Bateman in the book is also much more deprived. He's extremely homophobic and even murders a small child at one point. The movie cuts out most of the homophobia and certainly doesn't show him harm any children.
3 The Lord Of The Rings: The Return Of The King
The Lord of the Rings trilogy is often considered one of the best book to film adaptations ever put on screen. It captures the sense of joy, excitement and adventure filled throughout Tolkien's novels. One minor criticism the final movie has been its long-winded endings, but it's actually shorter than it could've been. In the book there's a whole other sequence that happens towards the story's end called the Scouring of the Shire.
The book reveals that forces led by the evil wizard Saruman haven't truly been defeated yet, and they've travel all the way to the Shire to wreak havoc. Trees were destroyed, houses crumbled, and pollution spread all throughout the Shire. Fortunately the hobbits were able to band together and defeat them at the Battle of Bywater. The movie completely cuts this tragic event out and ends with the Shire being untouched by evil.
2 The Little Mermaid
It would be possible to make an entire list of Disney films that are way less dark than their original fairy tales but The Little Mermaid takes the cake for being the most drastically different. In Hans Christian Andersen's story, Ariel's journey is filled with struggle. When she becomes human it's far more grueling. Every step she takes with her new human legs hurts her, but she's willing to suffer through it for love.
Unfortunately, the story ends with the prince falling in love with another woman and Ariel dies from a broken heart. She's so devastated that she becomes transformed into sea foam and is lost forever. It's hard to imagine what the Disney film would be like if it ended like this.
1 Coraline
The Coraline film definitely pushes the boundaries when it comes to the appropriate level of horror for a children's film, but it's still less scary than the novel it's based on. In the book the Other Parents are far more terrifying. The film leaves in their creepy buttons for eyes but cuts out some of the more disturbing things. For example, the film shows when Coraline uses a cat to distract the Other Mother and escape, but it's not quite as gory as in the book.
The book describes how her faced is gashed open and black tar oozes out, not exactly something you'd see in a PG movie. Another thing cut completely from the film is the basement scene. The book tells of how Coraline falls through a trapdoor into the basement where she discovers that the Other Father has been brutally mutilated for giving too much information to Coraline. While the film is still a fantastic and creative adaptation of the book, there were a few spooky things missing.