loyalist(n = noun.person) stalwart - a person who is loyal to their allegiance (especially in times of revolt);
is a kind of admirer, booster, champion, friend, protagonist, supporter
A person who adheres to his sovereign or to the lawful authority; especially, one who maintains his allegiance to his prince or government, and defends his cause in times of revolt or revolution. [1913 Webster]
loyalist, n.
1 a person who remains loyal to the legitimate sovereign etc., esp. in the face of rebellion or usurpation.
2 (Loyalist) a supporter of Parliamentary union between Great Britain and Northern Ireland.
Derivative:
loyalism n.