Protector

Noun

1. Someone who protects or guards, by assignment or on their own initiative. A headmate who primarily fronts, or otherwise protects the system, in situations where the system is at risk of psychological harm.
2. A headmate who primarily fronts, or otherwise protects the system, in situations where the system is at risk of psychological harm.
3. A device or mechanism which is designed to protect.
4. One who prevents interference. (Can we add an example for this sense?)
5. A state or other subject under international law, exercising a protectorate over another subject in international law.