examiner, tester, quizzer (noun)
someone who administers a test to determine your qualifications
examiner, inspector (noun)
an investigator who observes carefully
"the examiner searched for clues"
A person who investigates someone or something.
The Examiner was a weekly paper founded by Leigh and John Hunt in 1808. For the first fifty years it was a leading intellectual journal expounding radical principles, but from 1865 it repeatedly changed hands and political allegiance, resulting in a rapid decline in readership and loss of purpose.