The most memorable villains in fiction are not the loudest — they are the quietest. They do not rage. They observe.
They do not threaten with words. They threaten with silence and then act with precision. To design a 'lowkey villain', start with their philosophy: what do they genuinely believe about the world that makes their actions logical to them? The best antagonists are not evil — they are simply operating under a different moral code.
Give them a habit, a ritual, something small they always do — a coin they flip, a phrase they repeat. Give them a single line of dialogue in your first chapter that tells the reader everything about them without explaining anything. The villain with aura does not need to announce themselves.
Their presence does it for them..