Creating Realistic Non-Humans
If I don’t like a piece of science fiction media, I often find myself saying that it was too focused on the humans. I get enough of that in real life. Give me the aliens.
Obviously this a little bit of a joke… but not entirely. For whatever reason, throughout a long life of sci-fi and fantasy fandom, I’ve been drawn to the outsiders and the non-humans. I got a degree in anthropology in part because of my obsession with learning about other cultures, and in sci-fi and fantasy I get to indulge that love in reverse: I get to create them from the ground up, with none of the rules of history and specificity that Earth cultures have. But I’m often disappointed in editing or watching or reading other media by cultures that are cliché, shallowly developed in ways that often don’t make sense. So I’m here to help you with that.
Start With the Basics
You probably have some concept of what story niche you need a creature to fill. Are they a mindless devourer, a haughty warrior adversary, or noble-but-distant ally for your heroes to cautiously rely on? How many of them are we going to meet in the course of the game or story or script? Are they potentially playable or POV characters, or only enemies, set-dressing or NPCs? The more time your story spends with these people, the more detailed you’re going to want to get about who they are, and the more you’ll need to embrace the fact that these people are individuals with their own attitudes, ideas, talents, and personalities. Which brings me to…
Avoiding the Planet of Hats Trope
The Planet of Hats is a world where every single inhabitant shares a certain trait. They’re all obsessed with gangsters, or effete artistic types, or hardened warriors. I won’t point fingers, because just about every sci-fi franchise and most fantasy series has this going on. It’s attractive shorthand – and didn’t I just say you needed to start out with what story niche you need these people to fill? This makes it easy! All of these people are noble-but-distant allies or haughty warriors or whatever. But… it also makes them feel very samey and unrealistic. If everybody in this society is a scientist, who’s making dinner? Who’s cleaning up the lab at night? If they’re all warriors, how is the laundry getting done? Even the Spartans had traders, and pillaging was more of a seasonal job for the Vikings than anything else – they went home and were farmers or traders and so on the rest of the year. No society can function on just one kind of work. They may try, but they’ll inevitably become unbalanced, which usually leads to revolution of some kind. If you want to show a culture teetering on the edge of that kind of upheaval, by all means go for it! But be aware that otherwise, someone needs to be growing food and washing the floor and changing diapers while everyone else is talking about art or philosophy.
Examine Your Assumptions, and Think About Subverting Them
If that last section sounded like I might be talking about gendered jobs, consider who you automatically assumed would be doing the lower-status, domestic work… and consider whether or not maybe some or all of those assumptions might be different in this strange new world you’re creating.
Get Down to Biology
Don’t be scared – you don’t have to have a doctorate in biochem to do the kind of biological work that I’m talking about. You just need to have a little curiosity, some mental flexibility, and an internet connection. Let’s say you want to have a reptilian society like I suggested above, and you want them to hatch out of eggs. Great! (I hope you’re not thinking of giving your female reptilians breasts, though, because if they don’t nurse, there’s no reason for them to have mammary glands. Please don’t do this.)

Since these people are reptilian, let’s also assume that they have some of the other traits we would expect from non-avian reptiles on Earth – let’s say they’re cold-blooded and have what is scientifically called a “horny epidermis” (scales, for us lay people). They’re going to need to shed their skin as they grow, then, and not be active in cold temperatures due to a lower metabolism that’s reliant on heat. I’m guessing their cities aren’t big on nightlife, given that second fact, and, given the first, they probably have to take time off from whatever they’re doing (work, making war, etc.) when the time to shed comes on them. Or, at the very least, they’re going to be itchy, irritable, and distracted during those times. How could the daily and yearly patterns of their culture and their lives be set up to accommodate those traits?
What else? They might have infrared (heat-sensitive) vision like some snakes, which could be interesting. Think about how different the world would look to you if you could see the visible color spectrum and also heat. Now think about how useful that could be in certain professions. An engineer with that kind of vision could find leaks in engine construction at a glance, and I bet a blacksmith with that kind of skill would be in high demand – particular if she’s highly adapted to hot temperatures. Maybe they can see when the human characters are sweating or have a fever.
How does being an egg-layer change their society from what we mammals would think is normal? They might be significantly less attached to their young, but that doesn’t necessarily mean they’re heartless – it just means they’re different from us. (If you’re interested in this idea, take a look at what Becky Chambers does with the Aandrisks and their social structure in The Long Way to a Small, Angry Planet.)
Consider Working Against Type
In general, if a piece of media presents us with insectoid or reptilian creatures, they’re going to be evil, while if the creatures are fuzzy, big-eyed, mammalian, or all of the above, they’re almost certainly going to be good guys. There’ve been a few counter-examples over the years (District 9 being an obvious one), but if you’re interested in doing something unusual with your creatures, working against audience expectations in this way can be a great way to break out of the mold and do something that will surprise, and therefore interest, your viewers.

Worried about alienating your audience with creatures who don’t look like what they expect? This can be trickier in visual media than in written media where you as the author have more control over what adjectives a reader associates with your creatures, but if you don’t believe me that it can still work, look at what Mass Effect did with some of their species. The horny-toad looking Krogan are rough and tumble, for sure, but they’re not baddies, nor are the Turians (who are a lot harder to classify but are definitely not fluffy), and they are generally (but not in all cases, because individuals!) allies and friends.
Of course, you don’t have to stay within the classic bounds of insectoid, reptilian, cat-people, and so on. Stretch yourself! Combine traits from different classes of Earth animal, or use more obscure creatures. Make sentient species based on sea stars or jellyfish, anemones, or slime molds. What about an intelligent culture whose people go through something like the chrysalis process that moths and butterflies do, or who carry their homes/defenses around with them like hermit crabs? What would that kind of culture look like by the time it developed cities or became spacefaring?
The universe is your petri dish, my friends. Go out and design interesting nonhumans to fill your worlds.
What do you think? Share your tips and tricks for writing realistic non-humans on our forum!

Jen Grogan
Jen Grogan is a writer, editor, web content specialist, and nonprofit administrator based out of Seattle, where she lives with her husband, two loud but adorable cats, and too many books. She’s written for Women Write About Comics and a few other online venues, but has not yet convinced herself to call any of her fiction manuscripts complete. As an editor, she encourages others to do as she says, not as she does. In her free time she enjoys knitting, hiking, calligraphy, leading school tours for the Seattle Art Museum, and traveling to find new places to hike and new museums to visit. You can find her online at jengrogan.com.