There are few rules of mainstream filmmaking more important than "give the audience what they want," because if studios want to guarantee those precious billion-dollar box office grosses, they need to send as many people home happy as humanly possible.
It's a cynical way to look at art, for sure, but there's a reason that the overwhelming majority of big movies don't stray too far from the basic expectation that the hero will eventually triumph over the villain.
But sometimes films lull audiences into believing they're going to be one thing, only to reveal themselves to be something else entirely.
That's certainly the case with these 10 films, all of which clearly knew what people were expecting and in some cases gave them the polar opposite movie instead.
For some of these movies it was most certainly to their artistic benefit, box office be-damned, while in others it represented a smug attempt to trick viewers, who weren't exactly thrilled at being taken for a ride.
Though denied gratification can be a good thing, these films all left quarters of their respective fanbases deeply disappointed at what they didn't get...
The marketing for Ridley Scott's Prometheus promoted it as effectively a direct prequel to Alien, implying that the events depicted in this new film would dovetail directly into those of Scott's 1979 original.
But as it turned out, that wasn't the case at all.
While Jon Spaihts' original script was indeed more of a straight-up prequel, the decision was ultimately made - by either Scott or Fox - to have Lost's Damon Lindelof rewrite the script into something less explicitly linked to Alien.
Fans were left frustrated that they were sold an Alien prequel only to end up with an adjacent sort-of prequel that refused to commit to fully teeing-up the events of the entire series.
Shifting the setting from the original film's planetoid LV-426 to the moon LV-223 felt like an act of cowardice, as though Lindelof and Scott wanted to more-or-less imply what happened prior to Alien, yet with plausible deniability to uncouple it from Alien if it didn't go down well with fans.
Frustratingly Scott pulled this again with sequel Alien: Covenant, which rather than follow the thread of Elizabeth Shaw (Noomi Rapace) visiting the Engineer homeworld, killed her off-screen and basically delivered a schlocky slasher movie rehash of the original Alien.