A person who watches over another.
A tutelary angel watching over a particular person in monotheistic contexts.
A person who is employed as an armed guard, enforcer, or mercenary and who is prepared to use gunplay or similar violent methods in order to assert the interests of his or her employer.
A person who is employed to advance the interests of his or her employer, especially in a vigorous manner using such methods as political lobbying, legal advocacy, or persuasion.