3 free underrated sci-fi movies on Amazon you should watch in May 2025

The only thing better than a great sci-fi movie is one you can stream for free, without a subscription. These three underrated sci-fi movies on Amazon Prime Video are free and can be streamed this month.

Previously, Amazon had these titles under its Freevee umbrella. But with the Freevee brand now gone, you can find these free films tagged as “watch for free.” If you’re looking for something in the sci-fi genre you can watch without paying (but with ads), you don’t even need to dig through the offerings, because we have highlighted three great titles for you right here.

Need more recommendations? Then check out the best new movies to stream this week, the best movies on Netflix, the best movies on Hulu, the best movies on Amazon Prime Video, the best movies on Max, and the best movies on Disney+.

Dark Skies (2013) 

Produced by Blumhouse Productions, the production company behind some of the best horror movies, including films like Paranormal Activity, Insidious, The Purge, and Get Out, Dark Skies is about a typical suburban nuclear family that starts to experience strange events in their home. The kitchen is weirdly rearranged overnight. The house alarm goes off, indicating a breach at every single entrance. One day, hundreds of birds crash into the house. 

Once odd things start happening to the family members, mother Lacy (Keri Russell) does some research and thinks it might have something to do with aliens. Also starring Josh Hamilton (The Walking Dead) and J.K. Simmons (Red One), Dark Skies is suspenseful and intriguing, even if the plot gets lost at times.

Stream Dark Skies on Amazon Prime Video. 

Leviathan (1989)

Drawing comparisons to Alien and The Thing, Leviathan might be a copycat-type movie, but it’s worth watching for those who love movies that blend sci-fi with horror. Counted among the cast are Ernie Hudson (Ghostbusters) and Daniel Stern (Home Alone), and the story centers around an undersea mining operation that goes wrong when they come across a Soviet shipwreck called Leviathan.

A great claustrophobic thriller, Leviathan has gruesome, scary, and even funny moments to keep you entertained all the way through.

Stream Leviathan on Amazon Prime Video. 

The Mandela Effect (2019)

The psychological phenomenon known as the Mandela Effect has bubbled to the surface of late thanks to Charlie Brooker’s clever toying with viewers in the Black Mirror season seven episode Bête Noire. Two versions of the episode were released with different versions of a company logo, one showing “Barnie’s” and one showing “Bernie’s.” 

This concept of questioning reality is central to the plot in the 2019 movie The Mandela Effect, whereby grieving father Brendan (Charlie Hofheimer) swears he remembers events and facts differently from what others insist they were or appear to be today. Brendan starts to believe that he is shifting through parallel universes. From there, he becomes obsessed with the idea that maybe in one of these alternate worlds, his daughter Sam (Madeline McGraw) is still alive. 

Stream The Mandela Effect on Amazon Prime Video.