A person who takes it upon themselves to go after and punish the bad guys is often referred to as a vigilante. Vigilantes operate outside the legal system, believing that formal law enforcement is inadequate or ineffective. Their actions can be controversial, as they may lead to justice being served outside of legal frameworks, but they can also result in unintended consequences and further violence.
A person who sees an opportunity and takes advantage of it is called an opportunist. entrepreneur
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A Catholic.
A guardian takes care of his/her ward.
The ceremony after a person takes office is called an "inauguration."
Sonographer
That is called a bookie or bookmaker.
Sonographer
A person who takes up a certain space is typically referred to as an occupant.
A person who takes pictures with a camera is called the camera man.
They are called a Menagerie Man.
It is called gambling.