This is another thing that writers of fiction (especially writers of fantasy) often do poorly or don’t do at all. That’s a shame, since all it takes is a few tweaks in the right direction. It’s actually quite a simple process, and also pretty easy. However, the task of creating a whole new species can be pretty daunting.
The history of storytellers creating mythical races of animals and beasts is literally ancient. Most (if not all) of our concepts of what a mythical creature is or is meant to be come from old Greek or European myths. In fact, some mythologies share the same animals (for example: the Chinese has a dragon and so did the Europeans, but they both had much different concepts of dragons).
Sometimes an animal will garner a reputation based on how it is used in popular culture, much like how “elf” was an ambiguous term referring to many different things, with synonyms ranging from “goblin” to “fairy”. Now, it’s a pretty firmly established fact that an elf is either an immortal, good-looking, fair-of-speech sentient individual much like a human in some respects or an underling that works for Santa Clause.
Quick crash course on mythical creatures: usually, you have three kinds: domestic, hostile, and neutral. Hostile is by far your largest category, containing Sphynxes, Dragons, Chimeras, and Hydras (no, they are not dragons strictly speaking). Neutral is your next biggest category, but it’s still pretty small. This category usually details smaller animals like mythical bugs and insects, but can contain bigger ones like Ents. This kind of creature doesn’t play much of a large role at all. Domestic is by far the smallest category, and can range from something as small as a pet dragon (don’t laugh, I know some fantasies that do this) to something as big as a Rancor. These live at home with a sentient being for the owner, and domesticated creatures are just animals.
If you’re looking for some quick and commonly-known archetypes, go for Dragons (alternatively, they could be called “Drakes” or “Wyrms”). Dragons have been used for everything, from wise counselors to comic relief sidekicks. Classically, however, they have been used as villains. In my opinion, it’s what they’e best at. If you used one of the other classic creatures, though, you should have too much trouble making it work.
However: if you’re looking to create your own species of mythical creature, you’ve come to the right place. In order to do this, you have to follow one or two rules (but probably not both): draw from popular legend, or draw from real life. I would not advise you do both, but more on that below.
When you draw on popular fiction, be sure to draw on it with your own spin: it can be super easy to accidentally copy someone’s rendition of popular legend (because others have done this). More than one author has put the Phoenix into their story (Compare C.S. Lewis, J.K. Rowling and E. Nesbit), but in different ways. If you want to make your take on a mythical character of own, do so in a way that it doesn’t accidentally conflict with another author’s rendition.
If you choose to draw on real life, you have to be more creative. However, the chance of your copying someone is drastically lower, since you’re forced to come up with so many more ideas from scratch. Basically the process is grabbing (a) non-fictional creature(s) and adding a lot of your own ideas.
There’s a pretty good blanket tip out there to make your own mythical creatures: play on the creature’s (whether mythical or real) particular strength or weakness. Make it manifest in some way: if the snake is recognized as the wisest of animals, you might want to create a species of illusion-creating snakes that lure their prey in with hallucinations. Call them Siren Serpents. (For the record, I won’t be using this idea, and if you want to take it, be my guest)
Good luck, and happy writing!
Be sure to check out my latest novel, Book 1 in the Praetors of Lost Magic Series, and our Publications page. Until then, writers!