11. The Daleks (Dr. Who)
Exterminate! Exterminate! The Doctor is the last of the Time Lords and the rest of his race (with one or two exceptions) was wiped out by campy little levitating robots that make R2D2 appear downright stylish. But don't be fooled by the fact that they look like they were made by Texas Instruments in 1986; not many species have the power to wipe out the good Doctor's whole civilization. They exist only to destroy. And those vacuum cleaners are just the outer shell. The real Daleks are the tiny, creepy octopus-like critters living inside.
10. The Reavers (Firefly, Serenity)
Worse than the completely inhuman are those who've lost their
humanity. In a world with no alien species, Joss Whedon gave us
something more savage. Cannibalism has always held a special fright in
our culture. If we indeed are alone in this world, that doesn't
necessarily mean we're safe.
9. The Formic (Ender's Game)
Also known as Buggers, these insect-like creatures engage in an epic
and brutal space battle with humans in Orson Scott Card's novel. We
later learn that their ruthlessness stems from an ignorance of
humanity's sentience, paralelling Ender's own ignorance about the true
nature of his military training. The bug-like nature of the Formic lead
us down a rabbit trail in our assessment of good vs. evil, making for a
much more contemplative story than many on this list.
8. The Dominion (Star Trek: Deep Space Nine)
One of the first imaginings of a god-race that demands religious fealty
from other species, the Dominion were revealed to be Changelings who
reacted to persecution by "solids" with utter domination. With the help
of their subjects, the Jem'Hadar and the Vorta, they sought to rule the
Gamma Quadrant with an iron hand. With the ability to infiltrate their
enemies by mimicking their leaders, they are among the most savvy and
manipulative race humans have faced in science fiction, forcing
humanity to resort to treachery and biological warfare to survive.
7. The Colossi (Shadow of the Collosus)
This Playstation 2 game could be maddening to play, but that made it
feel all the more lifelike as you struggled to hang on to these
wondefully rendered giants and bring them to their knees. Not the
richest backstory, but ever since David felled Goliath, our desire for
a really, really big challenge has rarely been so well-satisfied. I
can't wait for the film.
6. The Goa'uld (Stargate: SG-1)
In most sci-fi imaginings, its only the future of humanity that's in
danger of enslavement or annhilation, but in Stargate, the Goa-uld have
been to our planet before. Thousands of years ago, the parasitic
snake-like creatures discovered that humans made good hosts and ruled
as the god Ra in ancient Egypt. But even more than the threat of
slavery, the thought of having another entitiy take over your body and
mind, while your consciousness remains intact but helpless, is a fate
worse than simple destruction. The Ori (the enemy race of seasons 9 and
10) and their unoriginal demands—more of our religious devotion—look
quite tame by comparison.
5. The Flood (Halo)
You know these little alien parasites are badass when you learn that
the ancient Forerunners killed themselves and every sentient being
around them just in order to stop the spread of The Flood. Turning
everyone into infectious zombies, the Halo baddies were a brilliant plot twist in a revolutionary game.
4. The Cylons (Battlestar Galactica)
In the campier predecessor to the more recent Sci-Fi series, the cylons
were metal robots trying to destroy humanity. But in Ronald D. Moore's
vision, they became something much more complex. They built "skin jobs"
that not only masqueraded as humans, but could also fall in love with
them, fight alongside them and betray them. Still, with an endgoal of
human extinction and a track record of wiping out all but 50,000 or
so, they rank pretty high on the list.
3. The Wraith (Stargate: Atlantis)
The Stargate creators needed to top the Goa'uld, and they did it with
the ghastly creatures called the Wraith. A grotesque genetic blend of
humans and alien insects, large hives of Wraith cull from
primitive human populations for food. But rather than good ol' fashion
eating, they suck your life out through slits in their hands—aging you
by the second and reducing you to smoking husk. When the Atlantis team arrives in the
neighborhood, the Wraith's holy grail becomes the billions of snacks on
2. The Sith (Star Wars series)
Not a species, per se, but a class to themselves as the weilders of
the dark side of the Force. Darth Vader. Darth Maul. And the great
Darth Sidious. Stronger than Jedi. So manipulative as to use politics
as well as mind tricks to rule the Galaxy. The Sith number in the few,
but those few are so villainous that they spread their darkness to all
known worlds. And the pinnacle of their evil is something called the
1. The Borg (Star Trek: The Next Generation, Star Trek: Voyager)
Collectivism might have been the American nightmare during the Cold
War, but it was only after the war ended that the ultimate
collectivists were imagined. Hurdling through space in enormous perfect
cubes, the Borg absorbed entire cultures and technologies wherever they
traveled, ever improving, ever evolving in their insatiable quest for
universal dominance. There is no "I" in Borg, and to be captured seems a
fate worse than death. Your individuality is destroyed but the body
lives on in service to the many. And, but for the fine crews of the
Enterprise and Voyager, resistance is futile.