The worlds of film and literature have gone hand in hand for years. If there is a big-name film, odds are there is a novelization of the script. Even more common are when stories make the jump from the page to the screen. Some of the best movie franchises, such as Harry Potter and Lord of the Rings, are book-to-film adaptations, and most know this fact. However, some very popular movies that the casual fan may not realize are book adaptations. Here are ten movies that movie lovers may not realize are based on books.

10. Forrest Gump

One of the most beloved films of all time is Forrest Gump. The film follows Forrest (Tom Hanks) as he lives through and causes various events throughout American history. The novel by Winston Groom more or less follows the same plot. There are some differences, however, some minor and some major. For example, in the book Forrest goes into space and becomes a champion chess player. Perhaps the biggest change is Jenny’s end. She actually survives the entire book and takes Forrest’s son with her as she runs away with another man. This is debatably sadder than the ending of the film, but both versions of Forrest Gump are definitely tear-jerkers.

9. Fight Club

Everyone knows the first rule of Fight Club. This didn’t stop Chuck Palahniuk from writing all about it in 1996, three years before the popular film directed by David Fincher. The movie has taken on a life of its own. So much so that many may not even realize the story of The Narrator and Tyler Durden exists outside of the silver screen. This is one book-to-film adaptation that didn’t change a ton. Some specifics, such as how the Narrator and Tyler met and certain character deaths, are really the only major changes. Most of the plot (including the iconic twist) is still intact. While there is and should only be one movie, there are actually three books. The first is a novel, while the other two are comic books published by Dark Horse.

8. First Blood

In the world of action movies, John Rambo is one of the most iconic heroes. When one hears the name Rambo, they imagine a muscle-bound Sylvester Stallone wearing a bandana, holding a giant gun, and screaming as he runs through the jungle. While most movies showcase this, the first film is much more grounded and somber. First Blood shows Rambo suffering the hostility many Vietnam vets received when returning to the States and finally snapping. The first film is based on a novel of the same name by David Morell. The book is much more gutwrenching than the sequels the film spawned. As with any book adaptation, the film does take some liberties. The ending is the best example, where Rambo meets a more definite fate than being arrested.

7. Psycho

6. Jaws

The film that created the modern blockbuster and put Steven Spielberg on the map was originally a novel. Jaws is an example of a book adaptation that has forged a legacy of its own. The novel was written by Peter Benchley and follows much of the same beat. The changes the film does make are for the best, most fans agree. For example, in the book, Chief Brody’s wife has an affair with Hooper. This pointless detour was omitted from the film, as was the Mayor’s mob ties. Jaws is known as one of the best Spielberg movies of all time, and fans of the iconic film should read the book.

5. Jurassic Park

Another Spielberg masterpiece that is actually a book-to-film adaptation is Jurassic Park. Michael Crichton wrote the original novel. Crichton was well known for making stories about what happens when man tampers with nature, but many agree this is his best. The novel has the same plot but some huge differences. Many of the characters that survive the film die in the book and vice versa. John Hammond is a selfish businessman who only cares about money in the novel. The film has a slightly more uplifting tone near the end, while the book goes out of its way to punish those who dare to play god.

4. Die Hard

Another classic action franchise that found its origins on the written page is Die Hard. Unlike other movie adaptations on this list, the source material actually has a different name. The original novel was Nothing Lasts Forever by Robert Thorpe and actually part of an ongoing series. The book was a sequel to a novel titled The Detective and featured the main character Joe Leland. This original novel was actually made into a movie starring Frank Sinatra, and the author hoped he would return for the sequel. Sinatra declined, and the book was eventually bought up by 20th Century Fox. The title became Die Hard, Joe Leland became John McClane, and action movie history was made.

3. Mrs. Doubtfire

One of the most beloved films from the late Robin Williams is Mrs. Doubtfire. The film follows Daniel Hillard as he disguises himself as a female nanny to be closer to his kids, whom he lost in a messy divorce. The novel by Anne Fine titled Madame Doubtfire follows more or less the same beats as the book-to-film adaptation. In the film, the children get to know Mrs. Doubtfire before discovering it is actually their father in disguise. In the novel, they pick up on it almost immediately. Also, Daniel is a voice actor in the film, while in the novel, he is an on-screen performer. The film overshadows the novel, but it does deserve a read as it has the same charm as the film.

2. The Shawshank Redemption

While many probably know this legendary film is based on a story, some casual fans may not. They may also be surprised this tale of hope and redemption comes from the king of horror. The Shawshank Redemption wasn’t based on a stand-alone novel but rather a short story in the compilation Different Seasons by legendary master of fright Stephen King. The short story, named  Rita Haywood and the Shawshank Redemption, tells a more compact version of the film’s events. The story is very similar save for a few changes. The most glaring is that Red, played by Morgan Freeman in the movie adaptation, is a white Irishman with curly red hair. Most of the story is the same, including the iconic prison escape sequence.

1. Shrek

Shrek is one of the best-animated films of all time and a fantastic spoof of Disney films. Many may not realize that the film is based on a storybook of the same name. The book by William Steig has some significant differences from the movie adaptation. The basic plot of a monster falling in love with a cursed princess after rescuing her from a tower is where the similarities end. Shrek, in the book, lives with his parents, who kick him out of the house specifically to go on an adventure. The storybook version is also capable of breathing fire, as well as being so ugly he can cook food simply by looking at it. The book is far shorter but still retains much of the charm that made the film so memorable. The film is one of many comedies streaming on Netflix.