10. Alien (1979)

Ridley Scott's frighteningly original space film worked gangbusters with audiences. Mixing the claustrophobic environment of the mining ship Nostromo along with a deadly stowaway space monster, Alien truly proved its own slogan: "in space, no one can hear you scream." While the film didn't quite make Sigourney Weaver a household name (that required the popular sequel Aliens), the innovative, award-winning creature design inspired by sketches by H.R.Giger made Alien instantly recognizable in popular culture.
9. Robocop (1987)

Infusing a good old police story with the nascent cyberpunk undertones of the early 1980s, Dutch director Paul Verhoeven used Robocop as an introduction of his explicitly violent style. Known for not pulling any punches (either visually or story-wise), Verhoeven used what was originally a standard action film to throw in some social commentary about police brutality, corporate monopolies and the effect of the media on the general populace. Relying on a solid script and great direction by Verhoeven (whose other notable sci-fi works include Total Recall, Starship Troopers and Hollow Man), Robocop brought new shock value to Hollywood, impacting many films that followed.

8. Back to the Future (1985)

It's always good to have some heavyweights in your corner when coming out with a new summer film. That's exactly what Robert Zemeckis got when he received backing from Steven Spielberg, who produced this delightful tale about a California teenager who finds himself traveling back to the year 1955. Zemeckis masterfully brings the complex intricacies of time travel to the average moviegoer, while providing a nice back story about changing one's destiny... or in this case preserving it. Good comedic performances move the story along at a great pace, while allowing Michael J. Fox to have fun no matter what time period.

7. Terminator 2: Judgment Day (1991)

Easily surpassing the original 1984 movie both in intensity and explosive action, Terminator 2: Judgment Day broke new ground visually with some advanced CGI  developed by the good folks at Industrial Light and Magic. Director James Cameron presents his trio of protagonists with the T-1000 (played with ice cold intensity by Robert Patrick), an unstoppable chameleon-like killer, making for the mother of all chase movies, keeping viewers riveted for two solid hours of pure Ah-nuld action. For fans who wish to see more, skip the weak third installment and move on to 2009's Terminator Salvation.

6. 2001 A Space Odyssey (1968)

When reclusive filmmaker Stanley Kubrick asked groovy hippies and intellectual audiences to expand their minds while watching this innovative piece, he received mixed reactions. Still, many praised the unorthodox narrative methods used to convey the essence of the story co-written by Kubrick and novelist Arthur C. Clarke (from his own book). Regardless of the diametrically opposed views on this cinematic icon of the 1960s, Kubrick's genius was undeniable when it came to directing a film about the nature of man, his place in the universe and higher planes of existence. 

    5. Close Encounters of the Third Kind (1977)

Having wowed the masses two years prior with Jaws, Steven Spielberg took a page from his own playbook and used the "less is more" approach in this film about friendly first contact with an alien race. Just as he hid the shark for three quarters of the above-mentioned movie, you don't really see much in the way of spaceships in Close Encounters, relying instead on the human response to such an event while tying in all sorts of unexplained phenomena of past 50 years as a bonus for viewers (the fate of the Flight 19 pilots lost in the Bermuda Triangle was a nice touch). Spielberg hints at the goodies consistently while following an obsessive Richard Dreyfuss, saving the best for last without ever giving too much away.


 4. Star Trek II: The Wrath of Khan (1982)

Unofficially the best of the classic Trek films, Wrath of Khan remains at the top of Trekkers' favorites lists, with its Moby Dick-style take on the revenge story. Re-enlisting Ricardo Montalban as genetically engineered superman Khan was a clincher for fans of the original series, ensuring a built-in audience going back 15 years. One of the best villains from the show paired with a major event causing the death of a beloved character makes for an enduring sci-fi staple, which has only been truly challenged as a fan favorite by the recent summer reboot of J.J. Abrams' Star Trek. 

3. The Matrix (1999)

Bringing new ideas to the human concept of reality and how humans perceive their own existence, The Matrix explored metaphysical aspects of our lives that we usually take for granted. The Wachowski Brothers laced their dystopian future with squid-like droids who hunt the last few human rebels as they seek to destroy the global artificial entity which has humanity plugged into a fake simulated world. Keanu Reeves and company go back into this simulacrum of 20th century America armed with superhuman skills, reflexes and, as Reeves' Neo states, "guns, lots of guns."

2. Blade Runner (1982)

Based on sci-fi writer Philip K. Dick's book Do Androids Dream of Electric Sheep, Blade Runner is the cinematic answer to a noir film set in a gritty future. The original release in 1982 had a Raymond Chandler-esque voice-over narration by lead actor Harrison Ford, which helped those unfamiliar with the novel get better situated. The 1992 Director's Cut removed this narrative as well as an out-of-place happy ending shown in the original while inserting a few key scenes floating the possibility that the hero of the story may himself be a replicant (the human-looking androids being tracked down in the film). Both thought-provoking and beautifully designed (the retro futuristic look in this film is awesome), it's no surprise that Blade Runner has become a cult classic in the last quarter century.

1. Star Wars (1977)

With its alien species, galactic governments, philosophical standpoints and imperial conquests, few films have the rich back story of Star Wars, a film that can only be called a "space opera" style story, replete with romance, rivalry, scum and villainy. And many, many sequels and prequels. A film which launched its own sustained industry (thanks to writer/director George Lucas' insight into securing his own toy and merchandizing rights), even triggering the birth of a loose religion based on the movie's Jedi teachings of non-violence, Star Wars will unfailingly be at the top of most people's lists of the best sci-fi film in the genre.