Karen

An officious interloper. Someone who goes out of her way to enforce some real or imagined rule or protocol without concern for it's propriety, legitimacy, applicability or Constitutionality when the situation does not otherwise call for her involvement. She has gone out of her way to insert herself into your business, and seems to revel in the opportunity to subjugate others to her will simply because it makes her feel morally superior.

I was walking by myself on an empty beach when off of a sudden this Karen appears out of nowhere and berates me for not wearing a mask.