protector

Someone who protects or guards, by assignment or on their own initiative.

A device or mechanism which is designed to protect.

One who prevents interference.

A state or other subject under international law, exercising a protectorate over another subject in international law.

(UK, historical) One having the care of the kingdom during the king's minority; a regent.

(Roman Catholicism) A cardinal, from one of the more considerable Roman Catholic nations, who looks after the interests of his people at Rome; also, a cardinal who has the same relation to a college, religious order, etc.