10. Invasion of the Body Snatchers (1956)

We've said it before, and we'll say it again: Don Siegel's Invasion of the Body Snatchers is THE ultimate paranoia film. This movie follows an outbreak of human body possessions as they progress from a handful of suspicious events to widespread zombification. It happens when an alien plant form begins replicating the residents of a small town and killing the originals. What results are pure automatons in the guise of everyday townspeople, guided by a mission to propagate their species until the entire planet has been overtaken and converted from humanity. We follow Dr. Miles Bennell through this nightmare as he attempts to escape a town in which literally anyone might be the enemy. When filmed by a cinematographer with the ability to evoke paranoia from practically any location, a story like this is basically guaranteed to become a classic.

9. The Thing

John Carpenter’s The Thing (a loose remake of The Thing from Another World) was critically panned during its theatrical release in 1982 and was considered a box-office bomb. However, the landscape has changed in the twenty-eight years since, and as a result, the film has become touted as both a taut science fiction film and a tense horror flick. Set in Antarctica, The Thing follows a group of researchers as they must face off against an alien life form that can assume the form of any living thing it touches. Its go-for-gross visuals (the result of some excellent make-up and effects) and paranoia-inducing scenarios (as it takes on the form of some of the researchers themselves) give The Thing an unforgettable level of tension. Carpenter’s film is purely atmospheric, relying on both the fear of the dark and the fear of the unknown to unsettle viewers. Its characters can trust neither each other nor themselves, and the shocking moments that Carpenter lathers on screen will keep its audience on edge as well.

8. The Host

Just when you thought Asian monster movies had lost their steam, South Korea brought us one that does everything right: The Host. The Host follows the attempt of a man named Park Gang-du to save his daughter from a monster from the Han River, the product of an American intervention in the country's scientific research. When the American military steps in to take control of the monster situation, everything continues to go predictably wrong. Gang-du becomes the victim of a wrongful quarantine, and with some invaluable help from his family, he must break out in order to rescue his daughter.

This is one of those rare films that can alternate between horror and humor seamlessly without diluting either element's effect. Its subject matter encompasses family, apathy, and the responsibility to live up to mistakes both big and small. It also provides a unique look at a monster created by pollution -- not a perfectly designed killing machine but a clumsy, bloodthirsty animal. This movie will jerk your tears, jerk your funny bone, and jerk you out of your seat.

7. Bride of Frankenstein

Bride of Frankenstein is not the most frightening film on this list, but its story is one of the best. As the first sequel to Frankenstein (1931), this movie picks up the story of Dr. Frankenstein and his creation -- the former as he attempts to overcome his desire to create life, the latter as he attempts to learn the rules of the world into which he has been so violently thrust. Boris Karloff in the role of the monster manages to make the creature's first words (including "friend," "good," and "smoke") believable in one of the most heartfelt scenes of a classic Universal monster movie, and Colin Clive in the role of Frankenstein once again turns in a performance that seems to teeter forever between genius and insanity. Add in Dr. Pretorius, the most devilish character of all of Universal's Frankenstein films, and you have a setup for a horror film both fun and dramatic. This is a story about friendship, partnership, love, and a poor soul's inability to hold on to any of those things.

6. The Fly (1986)

The Fly may be the grossest film on this list. A remake of a 1958 film of the same title, this movie follows a Dr. Seth Brundle's unfortunate metamorphosis into a giant, quasi-human fly after an accident involving a teleportation machine. This metamorphosis is the ultimate grotesque transformation, as Brundle slowly becomes a sticky, fleshy, bloody abomination. But the great thing about The Fly is that it uses its imagery not as an end but as a means to analyzing the body. Are you the same person if your entire body transforms and you meld DNA with a fly? What about if your constituent molecules are broken down and put back together? What makes us who we are, anyway? This film examines those questions in the light of our ever-increasing connection with technology, which makes it a fully successful integration of both science fiction and horror.

5. Frankenstein (1931)

Frankenstein is about as unforgettable a movie as you will ever see. Dr. Frankenstein's epic laboratory, the abominable reanimated conglomeration of body parts, the outbursts of madness ("It's alive!!") -- these things create such an impression on the mind that they have become ingrained in our culture, almost implacably influencing future depictions of Frankenstein's monster and mad scientists in general. What Frankenstein does best, though, is tell a story in which each of the opposing characters (Dr. Frankenstein and his monster) is a protagonist and in which each of these characters is equally horrifying to the other. Whether you want a fun movie or an intriguing one, Frankenstein is always a safe bet.

4. Godzilla (1954)

Godzilla (a.k.a. Gojira, 1954) has such raw power that it has almost the same effect today as it did fifty-five years ago. While it may not have you jumping out of your seat, this movie presents the viewer with an experience centered entirely on instilling terror. After a prehistoric monster is mutated and shaken from the bottom of the sea by atomic blast tests, the city of Tokyo is changed forever. Godzilla creates a mounting sense of dread as its titular monster attacks villages, boats, and finally the mainland in a devastating raid that leaves the city in a pile of rubble. It is a cold, depressing visualization of atomic weaponry, its effects, and the horrific capabilities lurking in mankind's subconscious.

3. Aliens

Imagine riding along with a handful of marines to a distant planet on which a human colony had been built -- except everyone is dead (save for one resourceful little girl), and when you arrive you find that the colony has been overrun by hordes of bloodthirsty aliens, evolved to do nothing but capture prey and use them as vessels for the their young. Aliens presents this scenario and offers no hope for triumph -- just a slim chance at survival -- as its characters explore and then try to escape the planet. The things you see in this movie -- such as the desperate plea, "Kill me" -- will chill you with horror. There's a reason Aliens is often touted of an example of sequels that turn out great. This movie never lets up.

2. Videodrome

Videodrome is without a doubt the most bizarre film on this list. This movie buckles the walls of science fiction, not to a breaking point but to a point at which it bends into surrealistic territory. The story begins with a TV station president's discovery of an underground broadcast of a depraved sadomasochistic television program, progresses into the realization that watching said program causes viewers to develop hallucination-inducing brain tumors, and finally settles in with the station president's gradual merging with television itself and his body's transcendence of reality. His world enters a tailspin as he develops a swollen, fleshy slit in his abdomen and grows a firearm in his horribly mutated hand. The intensity builds until the movie becomes a gruesome, explosive, bloody mess. Videodrome will have your brain spinning, your stomach churning, and your hands feeling for sudden bizarre growths. "Long live the new flesh."

1. Alien

Ridley Scott's sci-fi/horror masterpiece Alien is an example of the power of pacing and atmosphere in a horror film. When an interplanetary cargo ship is forced to stop and investigate a distress signal on an unexplored planet, a predatory alien life form finds its way on board, and the crew of seven will experience horrors they could never have imagined.

The time leading up to these events is spent suffocating the viewer in oppressive environments -- the claustrophobic ship, the black of space, and the fog of the planet. Then unsettling things begin happening: the discovery of large, leathery eggs aboard the source of the distress signal, the attaching of an alien life form to a crew member's face, the inability to remove said life form. Just when everything seems to be okay, just when we let our guard down, an explosion of horror is released, and the ever-diminishing crew finds itself being hunted by one of the most vicious creatures mankind has ever faced.

Throughout all of this, Alien never becomes action-oriented. It remains, until its end, a film centered on the horror of discovering something that wants only to hunt you down. These are people like you and me, placed in a situation unlike any that humanity has encountered. Alien is the ultimate achievement in sci-fi/horror.