When it comes to designing creatures, there are many different ways to approach the task. Everyone I’ve spoken to does it slightly differently and prioritises different aspects, leading to a sense of uniqueness even with two designs which have the same core elements to them. There’s no right or wrong way to approach it, but there are specific fundamentals which help make it easier to get into, regardless of whether you’re designing for fun, for a personal project, or for a client.
Thumbnails and Shapes
Thumbnailing is a useful exercise for many different types of art and illustration. It can help you work out the elements and composition of an image beforehand, or get an idea of how the colours you want to use will look together. It is also fantastic for working out the initial feel of a design of a creature, and allows you to focus on the overall elements and “balance” of a design without having to spend too much time drawing in the small details.
When working on the thumbnail stage, I tend to focus either on the silhouette or segmenting each bodypart roughly by a different colour. It doesn’t have to be very detailed, just a general idea; fleshing out the actual anatomy and small details like claws, different scale or furred areas, etc., comes later on. Focusing on the little elements can end up eating away at your time and be somewhat demotivating, especially if you get to the end and can’t use the design for its intended purpose.
Using simple shapes to construct a design, especially in the early stages, is often a great way to create a bold form - a lot of animals, even the most complex to illustrate, can be broken down into very basic shapes which are still easily recognizable. I find a good exercise is to pick an animal at random and try to render it in as few shapes as possible, or to pick a creature design I like and break that down into simple shapes. Doing this in small thumbnail sketches will help with both your ability to get a concept onto paper quickly, and your general understanding on what looks good at a distance.
Once the overall shape and feel of the design is set, I like to start fleshing out the actual anatomy of the creature. The approach I use will often depend on how I want the character to look at the end; if it’s a design grounded in realism, it’s good to look at a real-world equivalent even if that equivalent is loose.
For example, when designing the look of a phoenix, looking into the historical depictions and breaking the creature's design into separate elements can be a great start; taking the colours from a Mrs Gould's Sunbird, the body and wings of a Harpy Eagle, the neck of a swan, and the face of secretary bird - mixing and matching these, or even taking very loose anatomical inspiration from them can create a design which looks and feels believable, even though it's a hodge-podge construction of several very different kinds of birds, and matches some traditional depictions of the phoenix. However, sticking to tradition can sometimes feel cliché, and spicing things up is never a bad idea!
When it comes to creatures which have almost no real-world equivalent, say you’re designing an alien or a completely new type of lifeform for a project, this is where I usually start thinking about anatomy in the context of the creature's environment.
For example: “this creature lives in some form of water or liquid, but isn’t intended to look like a conventional fish.” If the creature isn't just carried along via currents, then it'll need something to propel and maneuvers in the water - this could be some form of tail or limb, or even something which acts akin to a boat propeller, for example. From that point, you can start to flesh out how its anatomy might look and work from thinking about how the creature would navigate and interact with the environment; how it would find food; how it would avoid being caught by a predator, etc.
In some situations, it may even be a worthwhile idea to throw out the concept of structural anatomy altogether. If you’re creating an extremely alien creature, or some sort of eldritch-inspired horror, if done right a creature which doesn’t follow what we would consider a conventional or understandable anatomical model could work fantastic to give that unsettling feeling. However, this can be very hard to pull off and is often fairly subjective. The creature will usually have to conform to its own rules, which can sometimes not be immediately obvious to a viewer.
Good questions to ask yourself as you design a character's anatomy would be; how does this creature move about its environment? How do they communicate (vocal noises, body language, etc)? Are they a predator creature, a prey creature, both, or something completely separate from the food chain? How do they defend themselves from threats?
Mixing and Matching
Somewhat related to anatomy, the concept of mixing and matching elements of not just other creatures, but objects, textures, themes, etc. in a design can lead to really unique and interesting results from both a design stand-point and a story stand-point.
A very good example of this can be found in some Pokémon designs; without its cannons, Blastoise would mostly just be a bipedal tortoise – still cool, but not as unique. Murkrow, which as a design is instantly recognizable as inspired by a real-world crow, combines visual elements of a witch's hat and broom to give it a subtle, but memorable edge. A non-animal based creature design with these elements can be found in Chandelure, a haunted chandelier Pokémon which draws heavy inspiration from the will-o'-the-wisps, ghosts lights in English folklore, and hitodama, the concept of a human soul which appears as a ball of fire floating through the night in Japanese folklore.
Mixing and matching textures, objects and creatures with the environment can bring some great results
This concept can both tie into environment, and anatomy; for example an animal that has colouration similar to the texture of wood grain is going to be successful at hiding and hunting in a dense forest; a rabbit-like creature with flowers growing out of its back is going to have a similarly good time at staying hidden in a flower meadow.
This can even be seen in real life and adapted; if you combine the concept of an Anglerfish and stick it on a small mammal which eats insects, you could end up designing a shrew with a bioluminescence nose which attracts moths as a means of hunting. This however would also leave it more susceptible to being spotted by predators - making the creature unique and somewhat magical, whilst also having a believable role in its environment.
The importance of this step will often depend on the intended use of this design; if it’s a stand-alone design and you just want to create a cool creature, it might not be as important (and there’s nothing bad about that!). If you love getting into the nitty-gritty and small details of designing a creature, then this step will be far more important.
It also ties in heavily into anatomy, and mixing and matching - and a lot of this requires asking yourself questions about how this creature interacts with said environment. For more mythical and one-of-a-kind creatures, this can be tricky as one individual's impact on an environment may be different compared to if there was a whole host of them; if you have a forest where a pack of small fire-breathing dragons roam, it’d make some sense if there was a mammal with some form of fire-resistance; however if it’s only one dragon making its home in that forest, it’d be unlikely an animal would evolve such a trait as the impact of the single dragon would be reduced.
Thinking about how creatures interact with the environment can help you make interesting design choices
How creatures interact with other creatures and sapient races can also be part of this step. Humans have bred animals to fill specific roles for years; working dogs, oxen and horses bred for their pulling strength, guard animals, etc. and some animals have been brought in to help with little domestication, for example the use of falconry in “pest control”, or leeches in medicine.
Humans have also used animals to help locate specific objects; you can pretty much run wild with this concept. A quick example could be a type of insect which commonly appears around areas infected with some sort of toxin. The insect will be feeding off this toxin, but the sapient creature will be using them as a warning sign that this area is potentially dangerous.
Getting into the slightly more technical side of drawing your creature early on is important, especially if you anticipate illustrating it multiple times. As with most subjects, breaking down your creature into basic shapes and building on top of it can really help with working out the perspective, and make the process of drawing the creature easier in the long run. Even if your style is more stylized or the creature seems simple at first glance, it’s important to get an idea early on as to how the creature would look in scenes or situations with more extreme perspective.
Make practice drawing your creature loosely from different angles
Perspective can also be a fantastic tool for helping get across information about your design - drawing your creature from a low angle will usually give it a looming, imposing atmosphere; which can help give a sense of gravitas or even an air of mystery to it, as very few animals are that big. Whilst perspective is more often considered in terms of backgrounds and scenery, using it in tandem with your creatures can help create interesting and appealing scenes.
Useful exercises I find when warming up to do anything perspective heavy is to draw the same subject (usually a set of simple objects) in different perspectives - sometimes with perspective-grids and sometimes without; for me this usually helps kick-start my brain into being actively conscious of subjects.
Gesture and Motion
Last but absolutely as important as the other points is gesture; this is something I’ve personally struggled with a lot throughout my time as an illustrator - capturing movement in a natural, interesting way can be difficult with a subject you have no real-world reference for, so I recommend finding a closest equivalent and studying from life.
When it comes to gesture, I usually take a similar approach to when fleshing out anatomy and find a real-world equivalent. Studying from videos is usually a better way of getting a feel for how something moves - still photos can’t always capture the energy behind movement, so I’d recommend taking your own videos of a pet or wildlife moving about and studying from that.
Taking your creature and doing quick, loose gestures drawings with them can give you a solid feel for how they’d move, how they stand, how they eat. It can help to highlight any issues or oversights with their anatomy, and how readable the form of the creature in a variety of situations.
Putting it all together
A lot of these points tie into each other, and I find that when it comes to designing creatures, or even illustrating animals, a lot of the process behind it can be boiled down to tying concepts together, taking elements from one thing and putting it in another.
If you know how to draw a cat, you can translate that anatomical knowledge to form a basic understanding of other animals, and adapt it to design creatures which use a similar plan. If you know how a variety of different birds move whilst in flight, you can pick and choose what type of movement best fits the type of design and work on from there.
It sounds cliché, but overall, when it comes to creature designs, there are really only three key features to improving at it: practise from life, try to stretch your imagination as far as you can, and most importantly, have fun.