The book isn’t always better than the movie, but most of the time (for me anyway) it is. I enjoy watching movies based on books to see how the story has been brought to life, and to find out whether the moving pictures match the ones built up in my imagination.

But some movies are so good you probably didn’t know they were a book first. Here are a few examples:

1. Die Hard (1988)

Based on: Nothing Lasts Forever by Roderick Thorp

Not only is the Bruce Willis Christmas classic based on a book, but Nothing Lasts Forever is actually a sequel to The Detective, which was made into a 1966 movie starring Frank Sinatra. They made a few changes to the story so it wouldn’t clash with the original movie – for example, in the book the main character’s name is Joe Leland, not John McClane.

2. Forrest Gump (1994)

Based on: Forrest Gump by Winston Groom

Forrest Gump the novel was not at all well-known before it became the massively successful, Oscar-winning movie. It was also pretty different – in the book, Forrest uses profound language, and the author originally wanted him to be played by John Goodman.

“No one believes me when I tell them Forrest Gump was a book that was way out there with him going to space with a monkey and crash landing back on an island with cannibals that he has to beat at chess to escape being eaten.”

3. Mean Girls (2004)

Based on: Queen Bees & Wannabes by Rosalind Wiseman

Tina Fey read Queen Bees & Wannabes – a self-help book for parents whose daughters are going through high school – and thought it had the potential to be turned into a movie. Obviously, though, the book is nonfiction, so Fey came up with the story and characters herself.

4. Jurassic Park (1993)

Based on: Jurassic Park by Michael Crichton

The book version of Jurassic Park actually originated as a screenplay, which author Michael Crichton wrote about a student who recreated a dinosaur. He decided to change the story after he decided that recreating dinosaurs would be an unrealistic academic venture, and would only make sense if it came from “a desire to entertain”.

5. Shrek (2001)

Based on: Shrek! by William Steig

You’d be forgiven for thinking Shrek – and its many, many sequels and spinoffs – was an original DreamWorks creation, but nope. It’s based on a picture book in which a terrifying ogre kind-of-accidentally saves a princess. The movie won the first ever Academy Award for Best Animated Feature, which is amazing.

6. Pitch Perfect (2012)

Based on: Pitch Perfect: The Quest for Collegiate A Cappella Glory by Mickey Rapkin

Similar to Mean Girls, Pitch Perfect was based on a nonfiction book. It was written by a senior editor at GQ, who spent a season following collegiate a cappella groups around the country on their quests for success. The Bellas were loosely inspired by the Divisi, an all-female a cappella group from the University of Oregon.

7. Mrs. Doubtfire (1993)

Based on: Madame Doubtfire by Anne Fine

The film adaptation of Madame Doubtfire follows Anne Fine’s young adult novel pretty closely – with one important exception: In the book, the two eldest children immediately recognise their new nanny as their father in disguise. Only their younger sister and mother are convinced it’s actually Madame Doubtfire.

8. Goodfellas (1990)

Based on: Wiseguy: Life in a Mafia Family by Nicholas Pileggi

The gangster classic Goodfellas is actually based on a nonfiction book written by journalist Nicholas Pileggi. It tells the story of Henry Hill, an informant who was once a member of the Mafia. Director Martin Scorsese believed the book to be the most honest portrayal of real-life gangsters he’d ever read.

9. The Shawshank Redemption (1994)

Based on: Rita Hayworth and Shawshank Redemption by Stephen King

The mega-acclaimed movie was actually based on a short story by Stephen King – you can find it in Different Seasons, a collection of four novellas. Oh, and one of the other stories in the collection was adapted into the classic coming of age movie Stand By Me.

10. Clueless (1995)

Based on: Emma by Jane Austen

Yup, teen classic Clueless is actually based on a Jane Austen novel. Obviously, it’s a modern retelling of Emma set in ’90s Beverly Hills rather than 19th-century England, but it’s cool to read the book and see what connections you can make with the movie that defined so many of our childhoods.

For the remaining 13, and some of them are corkers, you can visit the full list here: https://www.buzzfeed.com/movies-you-probably-didnt-know-were-books