Moderator
that would be a referee.
The word official is an adjective. It can also be a noun as in a person responsible for enforcing the rules in a sports game.
A person who studies the mind and behavior is called a psychologist.
A person who observes in an examination room is typically referred to as an exam proctor or invigilator. Their role is to ensure that the examination process is carried out fairly and efficiently by monitoring the behavior of the test takers and enforcing the rules and guidelines of the exam.
Editor.
A person who takes care of fish is called an "aquarist" or a "fishkeeper." They are responsible for maintaining the health and well-being of the fish in their care by ensuring they have a suitable environment, feeding them properly, and monitoring their behavior.
The foreman or manager is responsible for rectifying the situation when unsafe behavior is identified. Other employees should report any unsafe behavior they observe, either to the person perfoming the bahavior or to management.
Funeral Director or undertaker.
Consequences
A person who is at fault is commonly referred to as the "responsible party" or the "party at fault."
They're not - If they were, they'd be named as co-defendants.
Yes this is possible, especially when one puts up a behavior that was noticed before. Strange behavior is responsible for this. But before disliking the person you can as well talk to him about the behavior.