An individual or group at an organization, either private or public, who exposes illegal or unethical activity, or a behavior not seen as correct within an organization. The information brought forward can be seen as a violation of company policy/rules, law, regulation, or a threat to public interest or national security, as well as fraud and corruption. 

Whistleblowers are often employees or former employees of the organization, but can also be contractors, suppliers, or others with insider knowledge of the organization. These “insiders” will report the illegal activity to a regulator, to the media, or to those in positions of authority. This act of disclosing information to such entities makes them whistleblowers.