50 Shades of Grey.

The film is silly and mediocre but the book is next level terrible.

This may be unpopular but I was deeply disappointed in Shawshank Redemption when I read it. The movie is top tier.

Edit: In retrospect this doesn’t really answer your question as you asked about bad movies with a worse book and Shawshank is definitely not a bad film.

Starship Troopers was a far different story in each medium, but I think the movie is much more worthy of your time

I think you could make a credible argument that some of the Harry Potter books are worse than the movies. The best example that comes to mind is making fun of Hermione for wanting to free slaves, and the other characters claiming being slaves is in their nature or something. If you had only watched the movies instead, you'd get to see the slaves are miserable, most of the good team characters don't own slaves, and Harry Potter tricks a slave owner into freeing their slave.

Ready player one, though to be fair I didn't finish either version. I feel like percentage-wise I made it further through the movie, but only because the movie is less than 2 hours long. I made it to the 2nd chapter of the 2nd part and couldn't take the masturbatory prose any more. There's no self insertion on one side of the scale, Mary sue-ing in the middle, and ready player one sits on the far side of the scale.

Ready Player One I guess. There's a big difference between seeing a fuckload of pop culture artifacts on screen and reading multiple pages of somebody rattling off their knowledge about them. The worst part is that RP1 doesn't even really engage with the culture it utilizes in any kind of interesting way, it's all just surface level references that you'd learn from reading Reddit comment sections where people quote memes at each other. The movie on the other hand kind of makes it work because the pop culture artifacts aren't dwelled on, they're used more like an aesthetic choice, while the main focus of the movie is on its paint-by-numbers plot.

Fight Club, book is decent but the film seems a more complete package.

It's tv series not a movie but The Three Body Problem. The ideas are poorly thought out ass pulls to setup the weirdly specific situations the wittier wants.

At least the show makes the characters more interesting.

Harry Potter, the movies are at least wizards do wizard stuff even if the world is pretty boring to me. The books on the other hand, are just straight up strange and mean. Reading them as kid they just sucked, I have no clue why they are so popular outside of the movies.

The lord of the rings!

I love reading....I read a lot. But Tolkien's style just never worked for me, the movies were great.

I've started reading Jumper by NameDoesNotMatter. I would like to formally apologise about all the harsh things I've ever spoken about that film.

Fine, the cast is unlikeable and the action scenes are just fisticuffs in the air, but my god, in comparison to the teenage dreck that is the book, it's a masterpiece. At least they tried to build a credible back story for the main character.

In the book, he literally thinks everyone is out to sexually assault him (and somehow they seem to want to), he solves his problems by throwing money at it, instead of any actual creativity, and the author desperately tries to portray him as a mature-for-his-age adult, despite the fact that his first reaction to anything is crying followed by petty revenge.

I'm just flicking through the pages, pausing at any plot bits, and then flicking on.

Hunt for Red October. The book is great and for it's time had done amazing insight into modern naval warfare but the movie irons out a bunch of this which are a bit lame.

The Akula that kills itself with its own torpedo simply blows up because it abused its engine and another sunk when the titular sub rams into it.

The titular sub is later returned to the USSR.

The movie changes those and a few other things for a more exciting and satisfying outcome.

Jaws doesn't quite fit the prompt but although it's a good movie, the book is essentially a sub-par beach read. And there was no USS Indianapolis monologue in the book.

Stuart Little was the weirdest book you could possibly read, the movie managed to make it actually make sense while both were meh.

Hey now, I read Jumper as a teenager and it was one of my favorite books... Admittedly, adult me has never gone back and read it so maybe you're right, but I have read the sequels and I thought they were okay. The fourth one has Danny and Millie's daughter teleporting into Low Earth Orbit and using a bunch of real life space and satellite communications technology, which was cool because I consult in that industry and so it was like "Hey! I know what she's doing and that would work!" or even "I have a client who's working on something just like that!"

It doesn't fit the prompt because they're actually both really good, but the movie Contact is better than the book. Carl Sagan wrote in a very rambley, wordy way (kinda like how he talked). He spends like two and a half pages describing Palmer Joss's tattoos or Ellie Arroway's hair. So much of the stuff in it is so cool, but it's very hard to read. I've tried three or four times in my life, and I've ended up skipping around and just reading random parts of the story.

the Sookie Stackhouse novels vs. True Blood. the show got dumb but the books go off in so many more ridiculous directions. I quit watching the show after 3 seasons because the repetitive sex/violence juxtaposition got to be boring, but I still have to recognize that the show writers at least had restraint. also, Charlaine Harris writes like my foot

I don't know about worse, but the Eragon books and movie are equally terrible.

This is a show and not a movie, but definitely The Magicians. The show is pretty incredible, and more or less abandons everything wrong with the original. The books mostly spend way too many pages following all the MC's petty grievances, and he's like a massive incel.

I'm gonna mention "How to train your dragon". I actually preferred the books, but they are very different and I know many people who much prefer the movie.

Starship Troopers.

Babylon AD (the book is called Babylon Babies). I thought it was bad editing that made the end of the movie confusing. No. Turns out they took the actual ending of the book, toned it the fuck down and filmed it.

Not sure they could have filmed the part where the hyper-evolved babies take their comatose mother's consciousness, stuff it in an experimental space station and launch it towards the galaxy at 10% of light speed.

The classic would be fight club, I think even the author has said they enjoyed some of the symbolism that was added.

Howl's Moving Castle. Not that I didn't enjoy the book, I just preferred the movie more.