The objective of a movie trailer above all else is, of course, to gets butts in cinema seats and ensure a given film delivers on the studio's commercial expectations.
This is most often achieved by showcasing its appealing cast, neat action sequences, state-of-the-art visual effects, and so on. But sometimes studios decide, for whatever reason, to give away some of their movie's more compelling secrets in the damn trailers.
Perhaps the studio is worried about a soft opening weekend at the box office and wants to ensure audiences know some of the fun surprise that are in store.
After all, studies consistently show that the vast majority of casual cinemagoers like to know exactly what they're going to spend their hard-earned money on, and being spoiled isn't a major concern by comparison.
Even so, for those viewers who prefer not to know the big secrets ahead of time, it's enormously frustrating that these 10 films freely dropped massive spoilers for their most epic and unexpected moments like it was no big deal.
Studios will do anything to get their movies in front of as many paying eyeballs as possible, even if they might diminish the experience for other viewers in the process...
10. What The Predator Looks Like - Predator
Much of the thrill of John McTiernan's Predator is the mystery of the titular creature's appearance.
The film's slow-burn approach conceals the Predator's design for the vast majority of the movie, keeping it off-screen and having it use its nifty cloaking tech to avoid being seen.
It isn't until the third act that we catch actual sustained, lingering glimpses of the Predator's uncloaked form, yet the film's original theatrical trailer just went and gave the damn reveal away for free.
A flurry of clips near the end of the trailer blatantly show the Predator facing off against sole survivor Dutch (Arnold Schwarzenegger) in the film's climax, effectively ruining the mystery for anyone who saw the trailer beforehand.
Though you can argue that the audiences of 1987 would have likely only seen this trailer once or twice in cinemas before seeing the film - this being the pre-Internet era and all - the trailer clearly didn't need to show anything more than the Predator's hand to lure audiences in.