CBR's 31 Days of Halloween is a daily feature highlighting our staff's favorite horror movies to watch during the month of October. Reader, beware - you're in for a scare!

Science fiction and horror make for a perfect viewing combination, crafting dread from the unknowable expanse of space and paving the way for fantastic and alien creature designs. No movie has done this better than 1979's Alien. With its truly creative character design, evocative worldbuilding, and subtly-crafted scares, the sci-fi/horror film that made director Ridley Scott a household name has earned its place in the horror hall of fame.

Decades after its release, Alien now has three sequels and two prequel movies, along with a successful crossover series with the famous Predator franchise. With a television show in the works and an array of tie-in video games available to play, Alien has spawned not just a franchise but a devoted fan base -- and for good reason. The movie holds up, even while the computer technology and constant smoking scream that it should be outdated. Instead, Alien remains a perfect Halloween movie, the source of any number of horror tropes and a profoundly cool watching experience.

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What Is Alien About?

Alien Sigourney Weaver as Ripley

The commercial spacecraft Nostromo is headed back to Earth after a successful mining operation when the onboard computer detects a signal. The crew is awoken from hypersleep to investigate its source on a nearby alien planet. There, they find the remnants of a long-dead civilization -- the source of the signal that disrupted their sleep -- along with some peculiar eggs. When one crewmember gets too close, the egg hatches, and the nascent creature attaches itself to his face. The explorers quickly return to their ship for medical treatment, bringing the alien creature inside with them.

Here, Alien shifts from an eerie and epic sci-fi story to claustrophobic horror. After the face-hugging alien hatchling detaches, the crew thinks everything might go back to normal -- until a brand new creature bursts out of the poor man's chest. Soon, the alien evolves to a much more sinister and iconic form, picking off the crew one by one while hiding throughout the ship. The dwindling survivors must destroy the alien, but it seems like not all the Nostromo's crew members are on the same side.

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Why Ridley Scott's Alien Is Mandatory Halloween Viewing

Alien John Hurt Facehugger

The first half hour of Alien could belong to a very different movie, a 2001: A Space Odyssey-esque slow-build science fiction epic, before it shifts gears to body horror and jump scares. Either movie alone would have been interesting, but together, the two halves of this story become even more compelling. Part of what makes Alien so successful as a combination of genres is the masterful visual storytelling from Ridley Scott and his team of designers and effects artists. They build up a whole ancient culture to give the Xenomorph history without getting bogged down in lore drops.

None of that should downplay the horror of Alien, however. There's a shift in scale, moving from the wide expanse of outer space and strange alien worlds to the confines of the ship's air vents -- agoraphobia juxtaposed with claustrophobia. Not only does the content contract, but the camera angles do, too, making the rising danger feel all the more imminent. In these dread-inducing spaces, Alien throws some genuinely cool monsters at viewers, with each different stage of the H.R. Giger-inspired Xenomorph's life cycle somehow scarier than the previous. With the addition of secret robots and some surprisingly successful practical effects, Alien delivers on the fx.

The talent on display in Alien helps sell the strangeness and scares. Featuring an all-star cast in career-defining roles, Alien brought attention to Ian Holm decades before his role as Bilbo in The Lord of the Rings and a pre-Ghostbusters, pre-Avatar Sigourney Weaver. John Hurt delivers one of the most memorable performances of the movie -- and maybe the horror genre -- when unleashing the chestburster into the Nostromo's kitchen.

Featuring one of the most epic final-girl scenes in horror history, the story of Alien also makes the movie worthwhile. With twists that'll keep first-time viewers guessing about the real threat, the movie also features characters that are a joy to watch. Seeing Ripley constantly make the right move and get shot down by the (mostly) men surrounding her feels too real, as does her devotion to the ship's cat Jonesy, the only other survivor of the alien rampage. Ripley's never been more relatable than when futilely trying to enforce quarantine guidelines that would have kept everyone safe.

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How to Watch 1979's Alien - Is it Streaming?

Movies Alien Chestburster Scene

For those interested in diving into Alien for the first time or watching the sci-fi/horror again, the movie is currently streaming on Starz. A free trial subscription is available directly through Starz or as an add-on on Hulu and Prime Video. Those without a Starz subscription and not interested in starting one can rent Alien on Prime Video, YouTube, Vudu, Google Play, and Apple TV. Alien may be more than 40 years old but has never stopped being a truly compelling horror masterpiece, and it should absolutely be on must-watch lists this spooky season.