Photo by Lucasfilm/Warner Bros. PicturesWith George Lucas' animated epic Star Wars: The Clone Wars launching this week, we've compiled ratings from you -- the Yahoo! Movies user -- to rank the top sci-fi flicks of all time. Is your favorite movie on the list? Click ahead to find out.

Photo by Universal Pictures30. SERENITY

Writer/director Joss Whedon adapted his little-seen but much-beloved
sci-fi/Western TV series "Firefly" into a little-seen but much-beloved movie.

Photo by 20th Century Fox29. X-MEN: THE LAST STAND

The third movie adventure for Marvel Comics' uncanny band of mutants is the lowest ranking one, but the giant action sequences helped make it the highest-grossing film of the franchise.

Photo by Warner Bros. Pictures28. I AM LEGEND

In the most recent adaptation of Richard Matheson's classic novel, Will Smith battles not only an army of mindless, light-sensitive killers but also the solitude that threatens to drive him mad.

Photo by Newmarket Films27. DONNIE DARKO

A true mind bender. "Donnie Darko" spins the twisted tale of a disaffected teen told by a guy in a freaky rabbit costume that the world will end in 28 days.

Photo by 20th Century Fox26. X2: X-MEN UNITED

Working on a grander scale than the first, director Bryan Singer's second X-movie retained much of what was so entertaining from the original while adding more action and more mutants.

Photo by Touchstone Pictures25. DEJA VU

A police thriller with a time-travel twist, this film features Denzel Washington as an ATF agent investigating a terrorist attack. He soon becomes part of a secret government program that can literally peer back into the past.

Photo by Focus Features24. ETERNAL SUNSHINE OF THE SPOTLESS MIND

The science fiction element of the story -- a medical procedure that can selectively erase memories from your brain -- is really just a device to explore heartache in this touching, Oscar-winning drama.

Photo by Universal Pictures23. GHOSTBUSTERS

Proof that the best way to deal with metaphysical questions of the afterlife is to strap an unlicensed nuclear accelerator to your back, "Ghostbusters" isn't the highest rated movie on this list, but it is the funniest.

Photo by Warner Bros. Pictures22. V FOR VENDETTA

Based on the graphic novel written by Alan Moore (creator of the upcoming Watchmen), "V for Vendetta" presents a totalitarian England in the near future where the only hope for freedom is a masked, potentially psychotic anarchist.

Photo by MGM, Everett Collection21. THE TERMINATOR

With a mere $6 million budget, this now-classic action flick spawned two sequels, videogames, comic books, a TV show, and an upcoming prequel (that takes place 30 years after the original movie).

Photo by 20th Century Fox/Kobal, WireImage20. X-MEN

Burned by years of ridiculous movie adaptations, comic book fans were wary about seeing Stan Lee's beloved "X-Men" on the big screen. But this stylish and serious take sparked a new age of superhero movies that continues to this day.

Photo by 20th Century Fox/Kobal, WireImage19. PREDATOR

Roger Ebert said that this movie, "begins like Rambo and ends like Alien, and in today's Hollywood, that's creativity." Apparently, it must still be popular judging by how many of its stars became politicians.

Photo by Warner Bros. Pictures, Everett Collection18. SUPERMAN

The granddaddy of the modern comic book movie, director Richard Donner's adaptation was the first to combine (then) state-of-the-art special effect with a true respect for the source material.

Photo by Lucasfilm/20th Century Fox17. STAR WARS: EPISODE III - REVENGE OF THE SITH

After waiting decades for it, fans flooded theaters to see the big lightsaber showdown between Anakin Skywalker and Obi-Wan Kenobi. Which is impressive, since everyone already knew who won.

Photo by 20th Century Fox, Everett Collection16. ALIEN

A groundbreaking mix of science fiction and horror, "Alien" has been freaking out audiences for nearly 30 years. From its strong female protagonist to the shocking gore, it is still imitated to this day.

Photo by Columbia Pictures15. SPIDER-MAN

What made the movie of "Spider-Man" so successful were the same elements that made the comic book so beloved -- an average guy with real problems is given great power. With that, of course, comes great responsibility.

Photo by Universal Pictures, Everett Collection14. JURASSIC PARK

It's a movie that wasn't just a hit; it ushered in a new age of filmmaking. By seamlessly integrating believable digital characters into dynamic, live-action footage, Steven Spielberg once again changed the course of cinema.

Photo by TriStar Pictures, Everett Collection13. TERMINATOR 2: JUDGMENT DAY

James Cameron's vision of sentient robots killing off the human race seemed much more real thanks to some breakthrough technology, an action-packed script, and a freakishly fluid foe.

Photo by Walt Disney/Pixar12. INCREDIBLES

The fact that this is the only animated film on this list is a testament to Pixar's brilliance not only in animation but also in simply telling a great story.

Photo by Columbia Pictures, Everett Collection11. CLOSE ENCOUNTERS OF THE THIRD KIND

Steven Spielberg once again changes the course of movie history with this groundbreaking sci-fi flick about aliens that aren't evil invaders. Plus, Richard Dreyfuss manages to make mashed potatoes really creepy.

Photo by 20th Century Fox, Everett Collection10. THE DAY THE EARTH STOOD STILL

The oldest film on the list, this 1951 sci-fi classic is a chilling cry for world peace at the height of the cold war. It also features one of cinema's first cool robots: Gort. A remake starring Keanu Reeves is coming this December.

Photo by Universal Pictures9. E.T. THE EXTRA-TERRESTRIAL

Steven Spielberg channels the pain of his parents' divorce into this intergalactic fairytale about Reese's Pieces, flying bicycles, and mug-faced aliens with glowing body parts.

Photo by Warner Bros. Pictures, Everett Collection8. THE MATRIX

The Wachowski brothers wowed audiences everywhere with this movie featuring an unusual combination of cool effects, philosophical dialogue, and some of the best Kung Fu this side of the Pacific.

Photo by Universal Pictures, Everett Collection7. BACK TO THE FUTURE

Part of what makes this movie great is that the science fiction elements are essential to the story without ever overwhelming it. Watching it you realize that all teenagers could relate to their parents if they just had a time machine.

Photo by 20th Century Fox, Everett Collection6. ALIENS

James Cameron takes the Ridley Scott's original intergalactic fright fest and adds a lot more guns, explosions, and chest-bursting, acid-bleeding aliens. The result is a pure sci-fi adrenaline rush.

Photo by Lucasfilm/20th Century Fox/Kobal, WireImage5. RETURN OF THE JEDI

George Lucas brings his first "Star Wars" trilogy to a rousing end with this archetypical tale of familial redemption -- and the awesome military might of cute fuzzy Ewoks.

Photo by Lucasfilm/20th Century Fox/Kobal, WireImage4. THE EMPIRE STRIKES BACK

The middle chapter of George Lucas' hugely influential space opera is also his most human in spite of the fact that one of its most important characters is a bat-eared puppet.

Photo by Paramount Pictures3. TRANSFORMERS

In this film about giant evil robots that can turn into cars battling good robots that can also turn into cars, Michael Bay does what he does best -- wreck vast amounts of property with really cool explosions.

Photo by Lucasfilm/20th Century Fox/Kobal, WireImage2.STAR WARS

The first and best "Star Wars" has the sweep, characters, and action of some of the best tales ever told. And that's why after 30 years, it still captures the imagination of audiences all over the world.

Photo by Paramount Pictures, Everett Collection1. IRON MAN

The combination of good direction, great acting by Robert Downey Jr. and a seriously cool story has launched this summer blockbuster to the top of the charts. Is there a movie not on the list that should be? Be sure to add your ratings to your favorite film and let us know your thoughts in the comments below.