I'm working on a species of aliens for my story and they are very essential to the plot. They have to be only frightening and intimidating. My fear is that if I don't describe them properly then people will laugh where they should have some kind of fear response. If they aren't seen as a threat, then my protagonist doesn't get any brownie points for standing up to them. Any tips on how to describe something in a way that is scary and how I can make sure they won't be seen as like Jar-Jar Binks or something terrible like that? Help!
think of aliens you've seen/read about that are scary, and not at all funny--the xenomorphs in the Alien series, or the warrior bugs in Starship Troopers. since we don't have any actual alien life forms to go off of, virtually all aliens are essentially designed from earth critters. duck bills, floppy ears, and big woobly eyes aren't scary. hard exterior carapaces, small (or no, or too many) eyes, and spines are scary. more than anything, the aliens' actions and demeanor are what should show just how intimidating they are. in the David Brin Uplift series, there's a species of aliens that look like four-foot-tall teddy bears--covered in fur, with little round ears, stubby arms and legs, and cute little black eyes. and they're EVIL. they're manipulative, treacherous bullies. here's a description of them, the Pila. making aliens look scary is easy--base them off insects or reptiles. making them look adorable and still be intimidating as all hell takes a lot more work.
It may not be how you describe them directly, but how the characters in the story confronted by them, see and perceive the aliens. Not only their looks but actions, and even reputation, can have an impact on the readers. If the character's fear, or at least have a healthy respect for the aliens, that will flow through to the reader. Consider it as the difference between direct characterization and indirect characterization. Direct is where the author tells the reader about the aliens (that they're big, and ugly and scary and to be feared). Indirect is where the reader learns of the aliens through the actions of the aliens, and how others in the story see, perceive and interpret (or suffer/die) because of the aliens' actions.
Aside from just their appearance, the tone leading up to their being revealed can add to the fear factor. The entire setting and atmosphere, maybe a legend of the terrible things they do, can set up the reader and build the anticipation. Try to chill them a bit ahead of time so that the appearance packs a better punch and their own imagination amplifies whatever descriptions you make.
One of the most impressively blood-curdling aliens I read about were the Immotiles in Peter F. Hamilton's 'Commonwealth Saga'. A race of psychopathic, sentient immotile masses, as big as mountains, who produce small motile clones of themselves from a primordial soup, and are hell bent first on world domination, and later, on exterminating every other life in the Universe. The books have a lot of filler in them and can be frustrating to read, but if you can dig up the Immotile subplot from them, you can see some truly excellent descriptions of aliens who are scary not only in their appearance but also in what they do.
Just dont give too much away, dont elaborate or info dump characteristics, the best movie monsters are ones we hardly see till the payoff and even then the image is normally obscured. Let the reader minds and imagination play with the idea, it will scare them more than any writer or film maker that tries to show or describe the monster/alien.
If you can't think of any good aliens, think of instead, a scary monster. Then give it a spaceship. Like Dr who's weeping angels.
Their culture could be the scary part, for example an alien cult that harvest human kidneys. But as said by Supervenom above, the unknown is really what will make them scary. In Alien you barely see the Xenomorph, in the Thing the creature could be anyone or anything. Something intangible is much scarier then a hulking monster that forces the governments to band together making giant robots.
My best advice would be to rewatch the first Alien. Not for what it looked like, but for how it was portrayed. We saw bits and pieces, until the end. That's how you convey FEAR, by a LACK of information. Make your aliens ferocious by the stories associated with them, the fear they inspire in others, and the way they act. Then it won't matter what they look like, since we will already by feeling their presence. Give us details, sure, but fear that is beyond physical can be VERY effective.
I think the point that some of the posters here have alluded too is that psychology will make them a lot scarier than a pure blood and guts approach. Think of a Hannibal Lector from outer space.
As far as making them look frightening goes, you could give them a quality of an Earth-based creature that frightens a lot of people. As a lot of people (including myself) are frightened of spiders I wouldn't give them eight legs per say but something like extra eyes might be scary with a description like "they had several black, soulless eyes that looked directly at me"
