10 MORE Great Horror Movies You'll Only Watch Once

The main reason why moviegoers don't want to watch a great horror more than once is because it contains unsettling content. Although Annihilation fits that bill, there's another reason why Alex Garland's mind-bender could be considered a one-and-done: it's extremely confusing.

Annihilation's story follows four scientists who are sent to expedite an irradiated area called the Shimmer to retrieve a missing professor. However, their mission becomes jeopardised when they discover the Shimmer's properties meld the DNA of anyone within.

This 2018 Alex Garland picture has a lot of memorable sequences that are as horrifying as they are befuddling, involving slithering intestines, hybrid alligators, doppelgängers, humans turning into algae, genetic prisms, and a three-dimensional fractal called a Mandelbub.

Now, there are head-scratchers like 2001: A Space Odyssey and Mulholland Drive that become more understandable on repeated viewings. However, sitting through Annihilation a second, third, or fourth time will simply compound the confusion.

With that said, you may be tempted to rewatch it, simply to admire the beautiful visuals and terrific performances. But when you remember that nightmarish scene involving that skull bear, you'll probably reconsider.