A character built around a single trait or idea who doesn't change or reveal hidden depths throughout the story.
A flat character is defined by one or two dominant qualities and stays consistent from first appearance to last. The term was coined by E.M. Forster in his 1927 book Aspects of the Novel, where he distinguished between flat and round characters. Flat characters can often be summed up in a single sentence - think "the loyal best friend" or "the grumpy neighbor." They aren't necessarily bad writing; they serve essential roles by keeping stories focused and readable.
Not every character in your story needs a tragic backstory and three inner conflicts. Flat characters handle supporting roles efficiently, letting readers quickly understand who they are so the spotlight can stay on your main players. The trick is knowing when a flat character is the right tool and when you're accidentally flattening someone who should be round.
Crabbe and Goyle are classic flat characters - defined entirely by their role as Draco's dim-witted muscle, never revealing inner lives of their own.
Tom Buchanan stays largely flat - brutish, wealthy, and entitled from start to finish, serving as a foil to Gatsby's romantic ambition.
Many of the Capitol citizens function as flat characters, defined by their shallow obsession with spectacle, reinforcing the story's themes of inequality.
Give your main characters at least one internal contradiction or moment of genuine surprise. If you can sum them up in five words and nothing more, dig deeper.
Recognize that flat characters are a deliberate choice for supporting roles. A story where every single character is deeply complex can feel exhausting and unfocused.
Remember: flat vs. round is about depth. Static vs. dynamic is about change. A character can technically be flat and dynamic, or round and static.
Pick a flat character from a story you love and write a 200-word interior monologue from their perspective. Give them a secret, a fear, or a desire that never appears in the original story. Then ask yourself: does this added depth improve the story, or does it distract from what matters? This will sharpen your instinct for when flatness is a feature, not a bug.