From Dr. Frankenstein's infamous creature to the cast of Maurice Sendak's "Where the Wild Things Are," monsters have played a variety of roles in literature. Making up a monster can be a creative way to invent unusual character relationships and conflicts, as well as portray a society's fears and dangers through symbolism. Whether he's a misunderstood protagonist or a havoc-wreaking antagonist, you should consider both internal and external characterization, as well as elements of theme and allegory, as you create your own fictional monster.
Do a Character Sketch
Because a monster is a nonhuman character, you'll have to take special care to describe his physical appearance for readers. List the various characteristics that make him unique to your story, such as skin color, eye color, size and shape. You also can consider what identifying features the monster's body has, such as wings, a tail, sharp claws, large feet or unusual facial expressions. Your monster's behavior is also as valuable as his appearance in creating a convincing character. Try writing a description from the monster's point of view of what his life is like, including motivations and thought processes that could help you develop the threat he poses to the story.
Illustrate an Allegory
In literature, monsters often symbolize fears or problems in society, causing audiences to think about these issues in a different way as they read the story. Dracula, for example, is said to represent its original audience's fear of disease and foreigners, while the violent zombies in the 1968 film "Night of the Living Dead" are often seen as providing social commentary on the Vietnam War. Add to your monster's character depth by thinking about how he could illustrate a particular issue or type of character. Use personification, the tool of giving human characteristics to nonhuman entities, to lend specific personality attributes to your monster that relate to the story's theme.
Consider the Genre
Because monsters take on different roles according to the kind of story they appear in, thinking about your story's genre can help you create a monster appropriate for the plot. If you're writing a horror or suspense story, for example, the monster will likely be the antagonist. Try brainstorming threats the monster could pose to society, the fears he inspires in people and whether he or the story's hero will emerge victorious. If you're writing a children's story, you have more options, as monsters in children's books often represent empowerment and self-expression as well as danger. Whether he's a friend or a foe, the type of monster you've created likely will provide a clue to the story's genre.
Create the Natural Habitat
Deciding whether your monster will be an imposing force in a realistic setting or one of many monsters in a fantasy world can help you form both his character and the story's details. Thinking about your character's role as protagonist or antagonist, decide how the monster fits into the environment you're creating, using vivid detail to sketch a description of where the story takes place. Perhaps he's the only monster of his kind trapped in a world of humans, or one of many monsters staging a mass invasion of a major city. Try writing a description of the story's setting, including the sensory details that are unique to the monster's environment.