Question

what term refers to an unintended audience that came across someones work on accident?

Answer 1

Common terms are "unintended audience" or "accidental audience." Other variants used in media/communication contexts are "incidental audience" and, less commonly, "collateral audience."

- "Incidental audience" and "accidental audience" emphasize that people encountered the work by chance.
- "Collateral audience" is sometimes used where privacy or spillover effects are emphasized.
Use whichever fits your context; "unintended audience" is the simplest and widely understood.