Aliens have always had a way of stealing the show, whether they’re coming in peace, packing a serious punch, or just straight-up perplexing us with their out-of-this-world antics. These extraterrestrial beings have defined science fiction across decades of cinema, television, and gaming, creating some of the most memorable figures in pop culture.
The most iconic alien characters have become cultural landmarks, transcending time and galactic borders. From the comedic genius of Mork from Ork, nanu-nanuing his way into our hearts, to the wise, syntax-scrambling Yoda with his lightsaber skills and notable one-liners, they remind us that the final frontier is full of diverse personalities.
We're not just talking about alien characters from movies, TV, and video games based on their cool factor or how epic their battles are-though, those elements certainly add appeal. The best of these non-human characters transcend their cosmic origins to explore profound themes about human nature, technological advancement, and our place in the cosmos. It's also about the ones who make us think, laugh, and sometimes even question the very meaning of humanity-or alienity, if you will.
We’ve witnessed a galaxy's worth of extraterrestrial life forms, but only a select few, like the biomechanical horror of the Xenomorph XX121 from the Alien franchise or the honorable Predator with its intricate code, have integrated into the tapestry of our earthly collective imagination.
These cosmic entities are more than just simple cultural icons; they are powerful storytelling vehicles, whether they're invading Earth, offering technological wisdom, or simply struggling to understand human customs. Characters like Spock, the Vulcan science officer from Star Trek, and Superman, the last son of Krypton, use their outsider perspectives to provide unique reflections on human society.
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From the loyal Wookiee warrior Chewbacca piloting the Millennium Falcon to the complex evolution of the Xenomorphs, these otherworldly creatures have become as familiar to audiences as any human character-proving that compelling storytelling can indeed cross the boundaries of species, planets, and galaxies.
So grab your space helmet and prepare for liftoff as we count down the alien characters that have left an indelible mark on our world. These science fiction icons invite us to explore deeper realms of storytelling, challenging our perceptions and expanding the horizons of our imagination.
Be sure to vote on your favorites to help determine which character reigns supreme in the universe of space opera and horror-sci-fi hybrids.
Science fiction's portrayal of aliens has evolved from the simplistic "invaders from Mars" trope of early films to complex characters with detailed cultures and biologies. Early aliens often represented Cold War fears as mindless invaders, while the 1970s-80s saw more nuanced portrayals like E.T. and Spock.
Most Terrifying Alien Invaders in Science Fiction
Here is a list of some of the most terrifying alien invaders in science fiction:
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1. The Borg from Star Trek
We tried to avoid putting them on the list, but resistance was futile; it's The Borg. Star Trek's collective race of assimilating monstrosities is so terrifying because they represent the loss of our individuality. An ever-adapting fusion of flesh and technology, the Borg are a hostile force that seeks not just to eradicate humanity, but to enslave it, forcibly eradicating the sense of self and folding its victims into a homogenous hive mind.
Death is scary, but the kind of ego death inflicted by the Borg is arguably a fate worse than death. The implication is that you continue to exist, perhaps even conscious on some level of what you've lost, while everything that defines you is annihilated. The Borg represent our fear of erasure, of disappearing into a vast, flat, and uncaring bureaucracy, and are one of modern fiction's most deft updates to the existential horror first popularized in the fiction of Franz Kafka.
Also, they've got big cubes, the most horrifying of the geometric shapes.
The Borg Cube
Star Trek 8 First Contact - Borg Battle HD
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2. The Weeping Angels from Doctor Who
How long can YOU go without blinking?
The Weeping Angels are a race of predatory creatures, resembling stone statues. In their usual form, Weeping Angels resemble silent human-sized stone statues in the form of winged angels. Generally, their facial features are bland and serene and their proportions human-normal. However, as they close in on more aware victims they transform to a more horrific, bestial, and demonic aspect with wide-open mouths, vampiric teeth, and clawed hand.
According to the Doctor, the Weeping Angels "are as old as the universe (or very nearly), but no one quite knows where they come from." He also describes them as "the deadliest, most powerful, most malevolent life-form evolution has ever produced." Weeping Angels are unusual as predators in that they neither kill nor directly parasitize their prey. Their usual mode of feeding is to make use of time paradoxes - with a single touch, a Weeping Angel can send a person into the past to a point before his/her own birth, and can then feed off the "potential energy" of the years which that victim would have lived in the present.
Are you a fan of the TV series who isn't sure where to start with the books, or new to the Doctor Who universe all together? If that is you and you'd like to become acquainted with these terrible creatures (from the safety of your favorite reading chair) look no further than Jonathan Morris's Touched by an Angel.
In 2003, Rebecca Whitaker died in a road accident. Her husband Mark is still grieving. He receives a battered envelope, posted eight years ago, containing a set of instructions with a simple message: "You can save her."
As Mark is given the chance to save Rebecca, it’s up to the Doctor, Amy and Rory to save the whole world. Because this time the Weeping Angels are using Mark himself as a weapon to change history. Will the doctor stop Mark or will the angels feast?
The Weeping Angels
Star Trek 8 First Contact - Borg Battle HD
3. The Slugs from Robert A. Heinlein's The Puppet Masters
Want to be completely terrified? Just imagine gigantic slugs that can control your mind. That should do it and that is exactly what science fiction master Robert A. Heinlein imagined with “The Slugs” from his science fiction classic, The Puppet Masters.
First came the news that a flying saucer had landed in Iowa. Then came the announcement that the whole thing was a hoax. End of story. government were on the scene and disappeared without reporting in. And four more agents who were sent in also disappeared. So the head of the agency and his two top agents went in and managed to get out with their discovery: an invasion is underway by slug-like aliens who can touch a human and completely control his or her mind. What the humans know, they know. What the slugs want, no matter what, the human will do. And most of Iowa is already under their control.
The Slugs
Star Trek 8 First Contact - Borg Battle HD
4. The Thing from Who Goes There? by John W. Campbell Jr.
In a respectable fourth spot on our list of terrifying aliens is The Thing from “Who Goes There?” by John W. Campbell. “The Thing” from Campbell’s novella made such an impression on filmmakers that it was brought to the screen in the 1951 film “The Thing From Another World” and then again in 1982 with John Carpenter’s cult classic “The Thing”, which is likely where most of us became acquainted with this particular alien. This year we will be treated to yet another movie remake. Something to look forward to!
"Who Goes There?" is the John W. Campbell classic about an antarctic research camp that discovers and thaws the ancient, frozen body of a crash-landed alien. The creature revives with terrifying results, shape-shifting to assume the exact form of animal and man, alike. Paranoia ensues as a band of frightened men work to discern friend from foe, and destroy the menace before it challenges all of humanity!
The Thing
Star Trek 8 First Contact - Borg Battle HD
5. The Posleen from John Ringo’s The Legacy of the Aldenata
We have reached the top 5! In fifth place is the Posleen from The Legacy of the Aldenata, also known as the Posleen War Series, the fictional universe of one of John Ringo's military science fiction series. The Posleen are a race of genetically-engineered reptilian centaurs with crocodile-like heads. They were supposedly designed by the long lost race-the Aldenata-to be the ultimate warriors.
The Posleen invasion is shaped by their (over)engineered physiology - Posleen are omnivores and capable of sustaining themselves by eating a wide variety of organisms (including humans). They must eat almost constantly or starve. Inevitably, they exhaust the resources of every environment they inhabit, resulting in a phenomenon they call orna'adar - planetwide conflicts that always end in nuclear holocaust, with the survivors fleeing in starships to repeat the process on new worlds, leaving lifeless radioactive desert planets in their wake.
The Posleen
Star Trek 8 First Contact - Borg Battle HD
6. The Overlords from Arthur C. Clarke's Childhood's End
They come in peace... don't they?
Childhood's End by Arthur C. Clarke follows the peaceful alien invasion of Earth by the mysterious Overlords, whose arrival begins decades of apparent utopia under indirect alien rule, at the cost of human identity and culture. Clarke's idea for the book began with his short story "Guardian Angel" which he expanded into a novel in 1952. Childhood's End sold out its first printing, received good reviews and became Clarke's first successful novel. The book is often regarded by both readers and critics as Clarke's best novel and is described as "a classic of alien literature."
In the near future, enormous silver spaceships appear without warning over mankind’s largest cities. They belong to the Overlords, an alien race far superior to humanity in technological development. Their purpose is to dominate Earth. Their demands, however, are surprisingly benevolent: end war, poverty, and cruelty. Their presence, rather than signalling the end of humanity, ushers in a golden age . . . or so it seems.
Without conflict, human culture and progress stagnate. As the years pass, it becomes clear that the Overlords have a hidden agenda for the evolution of the human race that may not be as benevolent as it seems.
The Overlords
Star Trek 8 First Contact - Borg Battle HD
7. The Daleks from Doctor Who
"Exterminate! Exterminate!"
In seventh place on our list is The Daleks. The Daleks, are a fictional extraterrestrial race of mutants principally portrayed in the British science fiction television programme Doctor Who, and later immortalized in books.
They don't look nearly as menacing as some of the alien species on our list, but it is hard not to be terrified of something so completely emotionless. Not to mention, they came around at a time when we, as a society were generally pretty scared of robots, our collective early imaginings of which the Daleks could be said to closely resemble.
If you aren't familiar with the series, or if you are, but haven't read the books, you might not know where to start reading about these heartless and terrible creatures, hellbent on destroying us. We'd suggest Doctor Who: War of the Daleks by John Peel as the place to dive in!
The Doctor is repairing the TARDIS systems once again when it is swept up by a garbage ship roving through space, the Quetzel.
When another ship approaches and takes the Quetzel by force, the Doctor discovers that he and Sam are not the only unwitting travellers on board - there is a strangely familiar survival pod in the hold. Delani, the captain of the second ship, orders the pod to be opened. The Doctor is powerless to intervene as Davros is awakened once again.
But this is no out-and-out rescue of Davros. Delani and his crew are Thals, the sworn enemies of the Daleks. They intend to use Davros as a means to wipe out the Daleks, finally ridding the universe of the most aggressive, deadly race ever to exist. But the Doctor is still worried. For there is a signal beacon inside the pod, and even now a Dalek ship is closing in...
The Daleks
Star Trek 8 First Contact - Borg Battle HD
8. The Scum from Daniel Arenson's Earthrise
In eight place on our list are The Scum, the genuinely terrifying alien antagonists from Daniel Arenson's bestselling Earthrise Series. If you've yet to become acquainted, get ready!