Movie spoilers have become increasingly problematic for studios over the last 20 years as global Internet adoption has skyrocketed and practically everybody has a high-quality camera in their pocket.
As a result, it's more difficult than ever for Hollywood to keep a lid on its valuable secrets, to say nothing of the fact that large-scale productions employ thousands of people who can easily spoil the fun by leaking it online.
And for the vast majority of high-profile films, it's fair to say that the spoilers are out there weeks or even months ahead of time.
It didn't shock anyone that Benedict Cumberbatch was indeed Khan in Star Trek Into Darkness, while Star Wars: The Rise of Skywalker had its most shocking beats leaked a few weeks out, and Johnny Depp's "surprise" appearance as Grindelwald in Fantastic Beasts and Where to Find Them made headlines a short while prior to release.
As such, it's a truly formidable achievement when major movies manage to keep their epic plot twists and majorly unexpected reveals on lock, whether by employing an honourable crew or flat-out taking extreme measures to throw leakers and set spies off the scent.
Somehow, despite how easily these 10 films could've been rumbled, they kept hold of their biggest surprises until audiences were watching for themselves...
10. Everyone Dies - Rogue One: A Star Wars Story
Though the Star Wars sequel trilogy had most of its big rug-pulls spoiled weeks if not months ahead of time - enough that people actively assumed those Rise of Skywalker leaks had to be fake - the same wasn't true of the prequel spin-off Rogue One.
It's entirely possible that the availability of reliable leaks was hampered by an estimated 40% of the film being re-shot, but even so, most fans assumed Rogue One wouldn't offer up too many big surprises.
First and foremost, many fans quite understandably believed rumours that the film would be the first in a prospective trilogy of prequels, and so it seemed likely that, somehow, Jyn Erso (Felicity Jones) and a few of her rag-tag teammates would survive their daring heist for the Death Star's plans.
After all, it's hardly in Star Wars' wheelhouse to throw characters away after a single movie, and so fans were left gobsmacked by the movie's bleakly table-clearing "everyone dies" finale.
Despite many assuming that at least Jyn and probably Cassian Andor (Diego Luna) would make it out in tact, they ended up perishing along with everyone else, dying in each other's arms in one of the most unexpectedly depressing death scenes in the entire franchise.
It wasn't in vain of course, with the duo managing to transmit the Death Star schematics before Scarif was annihilated by Grand Moff Tarkin, but considering how easy it would've been to have these characters survive for a few sequels, it was a shockingly ballsy move.
And best of all, it wasn't leaked ahead of time, ensuring even the spoiler-hounds were largely caught off-guard.