BUILD A CREATURE: 5 Things to Keep in Mind while Building Monsters in Writing

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One of my all time favorite things about world building is creating monsters! I typically grab a mythical creature and modify it into something that’s mine, like what I did with my living vampires, but today I wanted to talk about creating an entirely new monster with no basis in mythology. That’s not to say a created monster can’t have some traits of a monster from mythology, of course, but I’m talking about going ground up rather than using an already-created monster as a basis.

I see other authors do this all the time, and will be delving into doing so myself at some point, particularly because the fae realm in my series tends to magically modify a variety of creatures. This can be used for sci-fi or horror settings too, however! My favorite ‘method of madness’ is magic, but alien species also work well for these thoughts too.

5. Relationship with other creatures

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Before I dive into appearance, I wanted to talk about relationships your monster could have with others. Particularly in the setting of mutualism, commensalism, and parasitism. Your monster might not necessarily rely on another, or be a parasite, but I always find these relationships in nature to be very fascinating. There’s several questions you can ask with regard to this.

Mutualism is where both species benefit from the relationship. A good example is clown fish to anemone. The clown fish is given a home while the anemone benefits from the fish scaring away otherwise unwanted predators. Ask yourself whether your monster will rely on another creature, and vice versa. Will it be food related? Habitat related? Perhaps, if your monster has higher intelligence, there can be some entertainment or stress-relief value with another creature that they pay back in their own way?

Commensalism is when one species benefits while the other is not affected. Eyelash mites on humans are a good example of this. They benefit from us (we give them a home and food from our secretions) but we don’t benefit from them, and we aren’t harmed by them. Do you perhaps have a GIGANTIC monster with a bunch of tiny monsters living on it and doing no harm, perhaps? Is your monster based on something like a bug that would live on one species, doing no harm, but impacting another?

Parasitism is what we know and ‘love’ with certain things like ticks, mosquitos, leeches…and vampire bats! This is where the parasite benefits while harming the host (although vampire bats don’t do much harm, they can technically spread disease). One might think vampires are a great example of a parasite monster! I actually turn mine into a mutualism creature, because the humans that let them feed are compensated monetarily and with protection for A LOT. In most cases, though, vampires are a great parasite example. How is your monster parasitic? Is it sapping energy from another creature somehow? Stealing a habitat and sapping resources? Feeding off of negative emotion? There’s tons of ways to go with it, and there’s many terrifying parasites out there.

Now, this is just a ‘parasite and host’ relationship segment, and there’s tons of other interactions in nature to be had as well. I wanted to mention this specifically, however, because I feel it could really get gears turning with regard to symbiotic relationships and how it could apply to fantasy monsters.

4. Use the bones

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One of the issues with speculation on actual biological organisms based on bones is that people tend to forget muscle and fat. This leads to inaccurate organisms, which is an issue for science, but a boon for creatives! Why? Well, take a look at an animal skeleton and come up with the most wacky-looking animal you can. After all, there’s theories that the cyclops was formed from an elephant skull, the hole in the ‘forehead’ actually a nasal cavity.

Messing up animals via skeletons is a no-no in science, but it’s a ‘go for it’ here. Picture the weirdest purpose for bone growths on an animal skeleton. Elongate points of the spine for spikes, perhaps. You don’t need to look at the skeleton at its baseline only. Morph things into uncanny, odd portions in your mind, mess up your animal enough to make it into some sort of terrifying. Turn nasal cavities into eyes, turn eyes into ears…ears into nasal cavities. The world is the limit, and studying skeletons to purposefully mess them up can lead to some creative monster ideas.

3. Base it off of a living animal (Build a humanoid too!)

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Before someone nails me for it, yes, I know there’s extinct hominins. I wanted to talk about the only species of Homo left, though, and that would be us. That’s why I’ll use this section to also talk about humanoid monsters. We’re animals still around, after all, and our general build is what we use for ‘humanoid monsters’.

That said, I’ll talk about them in a moment. Non-human animals are a great basis for monsters, because there’s so many that already look super eerie. We have our large cats and dogs, which we can add wings, spines, powers, and whatever else you want to. Don’t forget to explore other animals too, though. Let’s take a poisonous dart frog, enlarge it a ton, and remove the poison… but give it powers based on its color. Okay, one of them can keep the poison, but make sure to get creative!

People don’t take living animals as seriously, I feel, as some extinct ones, but they have just as much merit if not more. I mean, the shrike, an unassuming songbird, impales its prey on spines. Horses will eat chicks and are opportunistic carnivores. There’s a ton in wildlife research you can do, even just by scratching the surface, to create your monster. So…what will you add or remove from a living animal to make your monster?

As for humanoid monsters, these are straightforward and fun. I like adding sharp, dagger-like teeth to my humanoid monsters. There’s horn options, tail options, animal features (like ears, tails… etc). The furry community has some really cool humanoid designs that are bipedal, humanoid animals, which could count as monsters depending on how they work in a story, so that could be something to look into. Humanoids with less animal features and more on the ‘eerie additions’ could have morphed features, like longer limbs, multiple eyes, multiple functional limbs, and such like that. I love adding wings and claws along with sharp teeth to my humans, which is how I made demons in my universe. Well.. one species of them, rather.


  1. Shrike
  2. Tasmanian Devil
  3. Gaboon viper
  4. Poodle Moth
  5. Lowland Streaked Tenrec
  6. Tufted Deer
  7. Spider Crabs

2. Base it off of an extinct animal

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There were a LOT of wacky animals that are now extinct. The crocodile that could run on land, the elephant with a massive flattened trunk that worked as a mouth, the Liopleurodon Charlie… the list goes on! Doing research on these creatures can lead to excellent monster ideas, especially if you apply ideas to the number above to it. What additions can you make to an already odd animal to make it really monstrous?

Think about adding more horns to a T-Rex or wings to a raptor. We also don’t need to worry about being accurate, because this is fantasy! Featherless dinos are a thing of the past, but not in fantasy works. Of course, feathers on dinosaurs are cool… so feel free to add wings to that formula as well, come to think of it. What if we turned a brontosaurus CARNIVERIOUS and added some ‘monster things’ like horns or claws to it? It would be terrifying.

1. Behavior

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Similar to (1) on this list, but rather what your monster does as an individual along with behavior toward others. A mindless killing machine of a monster is valid, sure, but I don’t prefer that particular trope. I think nuance to monsters is amazing. Is your monster intelligent? Can it fight its instincts? What instincts does it have to begin with? Why is it considered a monster? Is it really a monster, or is it just misunderstood?

Particularly with monsters you grant with personalities, sentience, and free will, you’ll have to consider the morality of your monster. I don’t see “monster” as a negative term, though, whereas many people do. I see it simply as something with the capability to do a lot of damage, but not necessarily something that will. By that definition, humans are most definitely monsters…and most every animal we interact with, too!

Beyond how your monster acts with other creatures, though, you should ask how it interacts with its environment. Is it inherently destructive? If we moved it to someplace else, would it solve the issue? Is it fulfilling an environmental niche and is actually essential to a delicate ecosystem?

Finally, powers: What magical powers are you granting your monster, if any? Maybe not magic, but biological ‘powers’–like the cobra’s spitting venom, for example. Are you going with a biological basis for these abilities, or a magical one? Or even a technological one… is your monster somehow able to grant itself access to additional augments?

There you have it folks! Hopefully I gave you some things to consider when building a monster. Admittedly I might come back to this post when I delve into more than just monster-modification for my own works. I love the idea of making my own mythical creatures and can’t wait to do so for some future works. Cheers!

Want to learn about monsters & magic in my MAGICAL COLLEGE novel?! Check out my book here!

Published by Des M. Astor

Heya, I'm an author. Typically I write Urban Fantasy, and I only usually read in that genre as well. My author's website is both a writing blog and a showcase for my work. Check it out if you'd like.

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