I think there are 5 kinds of aliens.
The first kind are The Enemy. Their aim is to destroy our way of life. They come over here, they don’t speak our language, they look funny, they take our jobs, they use super-advanced weapons of mass destruction on us. They are malign and scary – but we don’t have to get too scared, because in the end we know they cannot win. If they don’t end up being defeated by the superior strength, virtue and/or intelligence of a Chosen Few, they will undoubtedly be vanquished by the common cold, an inability to use stairs, or as a last resort they will explode with incomprehension when confronted with our sense of humour. I can’t help feeling that these aliens are a product of colonial guilt. We’re scared that They are going to do to Us what We did to Them. We maybe have not yet learned to distrust stairs. This kind of story may help us to confront our fear of Others without having to project that fear onto real individual human beings.
The second kind of aliens are benign superbeings who attempt to sort out some or all of our major problems. They are usually either humanoid (tall, pale, thin, bigheaded, bald) or bodiless “more advanced” quasi-spirit-beings (tech version of angels). Their efforts at uplift often fail, or have unforeseen unfortunate results. These aliens may also be a colonial if-only; Noble Administrators who want to improve the lot of lesser races species – what we would like to have been. The Noble Administrators tend to show up our imaginative deficiencies, in that we can’t work out for real how to be SuperNice, or how to solve our current problems. This kind of story runs the risk of encouraging inertia, either through complacency (“I don’t have to worry about this; the Superbeings will fix it”) or through despair (“Not even Superbeings can fix this; there’s no point in me trying”). We seem to be not very good at imagining people who are better than Us.
The third kind of aliens are cute-but-fierce pets: Chewbacca, the Kzin. They tend to demonstrate at least some of the dog/Boy Scout virtues; they also tend to be not quite as good as Us at something important to the plot. They like us (give or take a few wars in the past). These aliens are the lesser races species we were hoping to find out there, so that we could be nice to them, and they could be grateful to us. This kind of story is probably most helpful for people with allergies to dogs/cats/etc.
The fourth kind of aliens are Weird Biology. Intelligent sea cucumbers. Intelligent hive-mind quasi-insect colonies. Intelligent vacuum-dwellers. Intelligent rocks. They come from a combination of human astonishment at the variety of known life, and the human tendency to personify everything. As beings they combine fascinating scientific puzzles (“What’s their metabolism? How do they communicate?”) with delightful exercises in empathy (“What does it feel like to be an intelligent rock?). The best of these stories are truly engaging and thought-provoking; the less good read like animated textbooks.
The fifth kind of aliens are Us.
Sue Thomason lives in rural North Yorkshire, near the sea, with an ex-GP and up to 5 cats. Varied involvement with written SF has included a handful of published short stories, reviewing for both VECTOR and FOUNDATION, co-editing an anthology of locally-based SF/F stories, and being Chair of Milford. She writes fiction mostly for her own entertainment and to find out what happens (often this surprises her). Her other interests include outdoor pursuits, gardening, classical/early/folk music, and collecting interesting or unusual paper clips.