Ever since humans first looked up into the night sky we’ve been speculating about what’s out there, and we’re showing no signs of stopping. Due to the mystery and seemingly endless possibilities that present themselves in space, the door is wide open for ideas. It is because of this blank slate that extra-terrestrial creatures will continue to be a dominating presence in cinema. Similar to the ever-expanding universe itself, there is always room for a new idea in the world of science fiction.

Aliens in cinema present themselves in a variety of ways. They can be innocent and cute like E.T., Starman or even the Prawns in District 9. They can be amusing and classic like in Paul, Mars Attacks! or Close Encounters of the Third Kind. There can even be whole worlds of alien creatures like in say Star Wars, Fifth Element, Star Trek or Men in Black. And then there’s the aliens with a darker side, a more ominous and deadly vibe about them. This is where the world of horror and science fiction collide into one fantastic sub-genre. Whole worlds and species have been created through this sub-genre and will undoubtedly continue to terrify and terrorize the human race. Not even the sky is the limit when it comes to what terrors lie out there and here are some of the best creations we’ve seen so far.

10. Sil – Species (1995)

Tagline: Be Intrigued. Be Seduced. Be Warned.

Using DNA from an unknown origin, Sil is the result of a gene splicing experiment that would make Fox Mulder swoon. Played by Natasha Henstridge (Ghosts of Mars), Sil is an alien with unique depth and origin story. A true stranger in a strange land, Sil has no idea where she came from, why she exists or where her path will lead. Guided by instinct, survival and fear, Sil reluctantly begins a journey towards motherhood that leaves a trail of bodies behind her. Boasting a strong supporting cast that includes Ben Kingsley (Gandhi), Michael Madsen (Reservoir Dogs), Forest Whitaker (Black Panther) and Marg Helgenberger (CSI), Species is a welcome addition to the sci-fi horror genre with a powerful lead alien.

9. The Blob (1958 & 1988)

Tagline: Scream now, while you can still breathe.

It crawls! It creeps! It eats you alive! It’s also one of the most influential alien creatures in all of cinema! In both incarnations of The Blob, the alien being slowly creeps around with seemingly no motive, no distinguishable features and no clear way to stop it. Our earthly weapons seem to have little effect and it can’t be reasoned with. Driven by an insatiable hunger and a will to survive, The Blob and its oozy impact have seeped into a variety of films. It’s also one of the best examples of an original and a remake being equally enjoyable and effective.

8. Mysterious Creature – Event Horizon (1997)

Tagline: Infinite Space – Infinite Terror

When the crew of the Lewis & Clark are sent to recover the ship and crew of the Event Horizon, the mission is already surrounded in mystery. Where has the Event Horizon been hiding for the last 7 years? What could have possibly happened to it? Before long, the rescue crew learn that they are not quite alone on this marooned ship, but with what is another mystery altogether. This mysterious creature reaches into the depths of the human mind manipulating thoughts, visions and actions. By these actions, it becomes terrifying in a way that few on-screen aliens are. The creature defies all logic and reasoning. It’s unfamiliar and hard to define. It’s motives and actions seem unnatural and all-encompassing simultaneously. The terror lies in the mystery and the inability to catalog what the creature on board the Event Horizon is, and even more, what it’s capable of.

7. The Crites/Krites – Critters (1986)

Tagline: They eat so fast, you don’t have time to scream.

The result of a prison transport gone awry (do they ever go right?), The Crites crash land in Kansas and begin to do what they do best; eat and destroy everything they can. While only 8 of these creatures make it down to Earth, that’s more than enough to wreak havoc and cause chaos. A perfect mix of Gremlin and Tribble, these alien creatures are as fierce as they are fun. Their antics seem to know no bounds and have resulted in 3 sequels, an upcoming 4th installment and a TV series! Maybe they have taken over after all…

6. Clover – Cloverfield (2008)

Tagline: Some Thing Has Found Us

Once referred to as “a monster for the MySpace generation,” Clover was a new monster for a new time. The combination of found footage aesthetic coupled with thoughtful and interesting character traits gave Clover a tight grip on young audiences. The mystery that surrounded Clover was left to simmer with audiences leading to rampant speculation and discussion regarding her origin, motives and fate. Oh, and multiple shared universe films of course. Abiding by the less is more mentality, director Matt Reeves, writer Drew Goddard and producer J.J. Abrams gave audiences just enough of Clover to be intrigued and terrified, but not enough to satisfy.

5. The Klowns – Killer Klowns from Outer Space (1988)

Tagline: In Space No One Can Eat Ice Cream!

It’s fairly impossible to pick just one favorite Klown character; each Klown has its own special style, technique and personality. These goofy aliens and their pizza, popcorn, shadow puppets and big top spaceship are some of the most unique aliens out there. We’ve all seen aliens with slimy skin, long limbs, big eyes and such, but who would picture aliens coming to Earth in clown form? The Chiodo Brothers apparently. This is a premise that could have gone horribly awry when committed to film, and yet somehow got pulled off with remarkable results. The premise is simple, the story familiar, but it’s the way it’s executed that has made The Klowns cult fan favorites.

4. The Female – Under the Skin (2013)

This intoxicating film tells the tale of an alien creature that inhabits the body of a young, beautiful woman played by Scarlett Johansson. As The Female hunts and seduces men to consume, she begins to absorb more than just sustenance. While their bodies may sustain and quench her thirst for energy, their humanity begins to seep into her as well. While the film is a trippy, cinematic experience of intense proportions, at its root, it’s a story of self discovery. We see the film from her perspective and because of that, The Female becomes a character that we can identify with, empathize with, and fear simultaneously.

3. The Yautja – Predator (1987)

Tagline: It came for the thrill of the hunt. It picked the wrong man to hunt.

Not only is Predator prime time Arnold Schwarzenegger, it’s prime 1980’s science fiction. A fantastic blend of horror, action and sci-fi, Predator offers us an alien that is strong, intelligent, determined and visually stunning. Unlike so many other cinema alien creations, The Yautja hunt not for sustenance or to reproduce, but simply for pleasure. They are trophy hunters on an intergalactic scale and humans are simply another head to hang on their space ship walls. The stunning creature design produced by the iconic Stan Winston has become one of the most enduring, and least changed alien characters over the last few decades. Why mess with evolved perfection?

2. The Thing – The Thing (1982)

Tagline: Man is The Warmest Place to Hide.

The concept of a being that hides itself in plain sight, assimilating and reproducing people that we know and trust is one of the most terrifying mind games that a creature could play. Similar to The Pods in Invasion of the Body Snatchers, The Thing possesses the ability to mimic, but in a next level horrifying way. The process of replication is not simple, fast or seamless for the creature. This process is ugly, methodical and ultimately…convincing. Based on a 1938 novella titled, Who Goes There?, John Carpenter and the film’s creature designers would take The Thing to a level never before seen on film. Just when you think things can’t get any worse, any more terrifying for the trapped Antarctic crew, the parasitic alien seems to one-up itself. To the very end, we as the audience are left wondering who we can trust, who will survive, and what will remain.

1. Xenomorph – Alien (1979)

Tagline: In space no one can hear you scream.

There’s really no creature in cinema, alien or not, that can compare to the Xenomorph from Ridley Scott’s masterpiece of science fiction horror, Alien. Utilizing the talents of visionary artist H.R. Giger, we get not just one finalized creation of epic proportions, we get a fully robust creation. From the very early egg stages, to Facehugger, to Chest Burster, Alien offers a creature that is terrifying every single step of the way. The Xenomorph is one of the best thought out and fulfilling alien characters we get in the genre. Unlike so many films where we get mere glimpses of a creature, Alien offers audiences the Xenomorph up on a slimy, silver platter. There’s no need to hide this incredible creature. The design crew on Alien executed a perfect being that provided a shockingly tense presence every single time it appears on-screen. Like it’s acidic blood eating through a space ship, the Xenomorph has penetrated pop culture in a way that has withstood the test of time and will continue to terrify indefinitely.

Which alien creatures leave you hesitant to approach that flaming crater in your backyard? How about the ones you’d like to find among your stuffed animals in your closet? Let us know on Twitter, or over at the Horror Fiends of Nightmare on Film Street Facebook group!