Don't Show Me Your Spider Aliens
I’m so tired of reading about octopuses and spiders and slugs!
The aliens were finally coming. I'd seen the signs of strange technology that couldn't be ours, the pods they launched into the atmosphere, and my favorite characters were hurdling deep into a shelter, anxiously watching their terminals for the first images.
Then the creatures’ leader exited its spaceship, and to my great disarray: "The thing reared back, and the two massive forelegs lifted and spread out. It reminded [me] of a spider raising its front legs."1
A spider! Are you telling me I stayed up until 2am for a stupid spider?
The Alien Problem (It's Not About the Legs)
The moment a writer says "it looked like a spider," they've broken the spell. My mind instantly snaps to that same spider I once tried (and failed) to swat off my bathroom wall. *Very* intimidating. The alien-ness? Gone faster than you can say "arthropod."
This isn't just about spiders. Octopuses, slugs, mushrooms – the moment you compare an alien to something we've seen on Planet Earth, you've deflated the whole mystique. It's like saying, "Well, it's hard to describe, so here's something from National Geographic. You know what those are, right? Great." And just like that, your reader isn't imagining the ungraspable; they're thinking about their last visit to the seafood market.
This shortcut might have worked in H.G. Wells' time when most readers had limited exposure to the natural world. Octopus martians with legs of metal were a thing of legends! But today, when we can pull up high-definition videos of deep-sea creatures or microscopic tardigrades in seconds, these comparisons feel painfully inadequate. We need something more.
I want scary aliens, not petting zoo rejects

The greatest alien encounters in literature don't rely on physical descriptions - they tap into something far more primal: our fear of the incomprehensible.
H.P. Lovecraft, for all his faults, understood something fundamental about alienness: sometimes, less is more. In "The Call of Cthulhu," we never get a complete description of the entity because human minds literally cannot process it. The narrator can only offer fragments, describing it as "a monster of vaguely anthropoid outline" before admitting that such earthly comparisons fail to capture its true horror. The terror comes not from knowing what it looks like, but from knowing that it's so far beyond our understanding that merely attempting to comprehend it can break us.
This approach reaches its peak in "The Colour Out of Space," where Lovecraft creates something so alien that it can't even be described as a color within our visual spectrum. The narrator struggles: "It was just a colour... like no colour anyone had ever seen... it wasn't any colour men know about." It's brilliant precisely because it forces our imagination to work with a concept our language can’t begin to express – a color that doesn't exist in our reality.
This is what real alienness feels like – that moment when your brain short-circuits trying to make sense of something beyond its evolutionary programming. It's not about counting legs or describing mandibles; it's about capturing that visceral "nope" moment when human consciousness encounters something it was never designed to process. When the mere presence of an entity causes your mind to recoil from things it was never meant to understand.
The Language Barrier
If you really want to make your aliens feel *alien*, make us struggle with their very existence. And nothing embodies this struggle better than Denis Villeneuve's "Arrival"2. This is a movie that understands that true alienness isn't about how many eyes it has – it's about how it perceives reality itself.
When linguist Louise Banks (Amy Adams) first encounters the heptapods' language, she faces a problem far more complex than "how do I say hello?" Their written language appears as circular symbols, where meaning exists simultaneously rather than linearly. Imagine trying to read a sentence where the end affects the beginning, and every part exists at once. It's like trying to understand a joke where the punchline and setup happen at the same time.
The breakthrough comes when Banks realizes she's not just dealing with a different alphabet – she's dealing with a fundamentally different way of experiencing reality. The heptapods' language is circular because their perception of time is non-linear. They don't see past, present, and future as separate things. Their entire language is based on knowing the end of a sentence before they start writing it. Try wrapping your human, chronologically-bound brain around that!
This is what makes "Arrival" so brilliant at portraying alienness. The challenge isn't just teaching aliens human words or learning theirs – it's about the mind-bending realization that language shapes how we perceive reality itself. The more Banks learns their language, the more she begins to experience time as they do, leading to the film's emotionally devastating conclusion.3
These are the kind of aliens we need more of in science fiction. Not creatures that look weird, but beings who force us to question our most basic assumptions about consciousness, communication, and reality itself. When your aliens think in ways that make human brains short-circuit, you don't need to show us those stupid legs, the fog was enough.
Endwords
Give us aliens that make our brains feel like they're running Windows 95 trying to open Chrome – complete system failure. Give us beings so foreign that even attempting to describe them in a Substack article would probably violate several laws of physics. Because in the end, real aliens shouldn't remind us of anything we know. They should remind us of how much we don't know, and maybe never can.
And please, for the love of all that's extraterrestrial, no more spiders. I've got enough of those in my bathroom.
The Mercy of Gods, James S.A. Corey
based on Ted Chiang's "Story of Your Life"
Spoilers for the ending: As the main characters are being evacuated from the camp, Donnelly (the physicist) expresses his love for Banks and they discuss life choices, and how they would change them if they could see their lives from beginning to end. Banks (who has seen her future) knows she’ll agree to have a child with him, despite having seen their fate: the little girl will die of an incurable disease, and Donnelly will leave her once she’ll reveal she knew from the start.
Stephen King says roughly the same thing in Danse Macabre, that the moment the author reveals the monster, the monster fails to frighten as much any more. I find that you're spot on regarding lazy descriptions, and your example movie ("Arrival") presents a fine example of an alternative approach where aliens are so alien in their behavior that their appearance doesn't even matter.
Excellent tips any sci-fi/horror writing! I have read Lovecraft and while we are used to thinking about tendrils and tentacles when it comes to his stuff, it’s true that he never quite gets into the specifics. The Colour Out of Space is proper creepy, I also enjoy the Dunwich Horror for a similar feel!