WordNet sense 1 (a person who is loyal to their allegiance (especially in times of revolt)):

loyalist

WordNet sense 2 (having rugged physical strength; inured to fatigue or hardships):

hardy, stout, sturdy

WordNet sense 3 (physically strong):

robust

WordNet sense 4 (firm in purpose or belief; characterized by firmness and determination):

resolute

WordNet sense 5 (used especially of persons):

stouthearted

WordNet sense 6 (possessing or displaying courage; able to face and deal with danger or fear without flinching):

brave, courageous