They're coming, you know. Are you ready? Will you know the Alien when it arrives in your small town, wearing your next door neighbor for a face? Will you fight for humanity, or will you succumb to their tawdry promises of unearthly riches and your neighbor's wife and teenaged daughter? We will be ready for them. We will fight them with every weapon at our disposal, and we will rid the Earth of these foreign monsters.
By these signs you may recognize the Alien. Study them closely. Our future depends on it.
THE LOST TRIBES
Aliens that are like ourselves, almost or exactly human, save for a superior technology and an interstellar government. While they may have some powers such as telepathy, teleportation or time travel, they are not all-powerful. These lost tribes are expected to be encountered in "peaceful" situations that emphasize the glorious destiny of the humans, or exalt the Earthman in some way, i.e. - the lost tribes come to Earth seeking refuge from some catastrophe in the latter case, or to admit Earth into the expanding Galactic Union. Beware men who buy suspicious numbers of white mice for pets, and women who are eager for sex.
THE GRAYS
We know them from the signs in our cornfields, from Uncle Jack's ultraviolet tattoos, from the lying truth of the government propaganda. They are everywhere, and they are studying us. They took Elvis, and now they know all our weaknesses. Almond eyes will show no mercy. They are the doctors of the Galaxy, always ready with dental drills and cranial implants. The Government knows.
THE GUARDIANS
They come on beams of light, in ghost transmissions from the cold heart of space, in dreams of savant children in dirt-poor Third World nations. They hold all the secrets worth holding, and they like puzzles. They will save us from ourselves, but only if we dismantle our nukes. Resistance is unwise.
THE LOCUSTS
In the ten thousand years of their history, they have moved from world to world, stopping only to rape each new planet, moving on when its resources have been extinguished. They crave our precious bodily fluids, our clean air, our fresh meat. Of all the offworlders, they are the most disdainful of human life, for it means nothing to them. Humans make bad slaves. Contact your local recruiting office.
THE RAPTORS
These are the ultimate human nightmares, the creatures like demonically misformed predators. They live to kill, acid saliva dripping from their clever jaws in anticipation of the human blood they have instinctively craved since the first of their species emerged from the fog on some faraway nightmare world. They are unintelligent, but frequently skillful hunters, often hunting in packs. They will be encountered on dead worlds, ghost ships, sunlit hells and rogue asteroids. They are best fought with fire, wielded by females.
Only you have been given this knowledge. Trust no one.
UPDATE - I feel so stupid. No sooner had I submitted this list, than I was /msged by Shoggoth, a brand-new noder who reminded me of the one alien I forgot - possibly the most important variety of all, and definitely one that our users should know about. So, thanks to Shoggoth, here are a few details on -
THE HAUNTERS
From hellish dimensions they come to our tiny world for souls and spirits. Their shapes are horrible to human eyes. Like primordial monsters they crawl gibbering out of colours that men were not meant to see, leaping from corners beyond Euclidean geometry, slithering in darkened forests half in our world, half in nameless Diluvian jungles. They and their human servants are everywhere. Beware silver boxes and inherited houses. Watch the sk - wait. What's that? What IS that, by Christ? Impossible. Defies logic. No, it can't be. It's horrible. It's coming this way. it knows me. calling my name, fear dripping off its teeth so many many teeth how can this be i've GOT TO SUBMIT THIS NOW, GOT TO TELL THE NODERS TELL THEM NOT TO LET SHOGGOTH BECOME AN ED - AAAAAAAAATHHHIHgjnriiiiiiiiiiikl./
If anyone knows how DejaMorgana can be contacted, please /msg a god. That sick fuck obviously needs to be hospitalized, but he seems to have left E2 for good. And, would everyone please extend a warm E2 welcome to Shoggoth, our newest god? Shoggoth is a very amiable Southern gentleman with an amazing South Seas tan and a truly remarkable library, and I'm sure he will enrich E2 greatly with his knowledge. Thank you, The Management.