A tutelary angel watching over a particular person in monotheistic contexts.
A person who watches over another.
One who minds, tends, or watches something such as a child, a machine, or cattle; a keeper.
A monitor assigned by the authorities to someone, such as a foreign visitor (to exercise control over their contacts with the populace) or a journalist or someone who is speaking to journalists (to monitor and control what they say).
A personal bodyguard.