A person who flies in space is called an astronaut.
They'd be called that person's relative.
That person may be called a victim. If the person does not survive, the person can be called a casualty.
a person who does not exercise is called a layman.
When a person imitates another person, it is called mimicking or copying.
A person that grows plants is called a farmer.
A detested person is called a pariah, a detested person, idea, or thing is called an anathema.
A person from Iraq is called an Iraqi.
The person is called the loser.
the person is called a chaufer
A person from Naples is called a Neapolitan.
A person in a story is called a character.