An ISO 9000 registrar auditor is an individual who works for a certification body or registrar and is responsible for conducting audits to assess organizations' compliance with ISO 9000 standards. These auditors are trained and certified in ISO 9000 requirements and auditing techniques. They perform on-site assessments of an organization's quality management system and evaluate its conformity to the ISO 9000 series of standards. The registrar auditor plays a crucial role in the certification process, providing an objective evaluation of an organization's quality management practices.