20 Sci-Fi Movies EVERY Film Fan Should Have Seen

One of the most famous sci-fi movies of all time - and, without question, the most famous alien movie of all time - Ridley Scott's Alien is rightfully considered a thrilling masterpiece that was revolutionary for the genre itself and a huge leap forward in terms of special effects.

With Sigourney Weaver leading the way with her career-making performance as the resilient Ellen Ripley, the film centers on the crew of the Nostromo and essentially tracks their reaction to the fact that they're stranded in space with a vicious extraterrestrial with a second mouth and acidic blood.

Of course the Xenomorph would go on to become one of the most iconic creations in cinematic history, with it playing more of a prominent role in sequels, but what makes Alien so damn terrifying is the fact that the creature doesn't actually appear on-screen all that much - which ultimately heightens that sense of dread because you never know when it's going to show up throughout the entire two-hour masterpiece.