Champion, one who combats or fights; specifically, in the Middle Ages, a person who took up the cause and fought in the place of another. Single combat was one of the ways frequently adopted to decide the right of a cause; and women, children, or aged persons were allowed to appear by a representative. At one time
the champions were looked upon as disreputable, being ready, for hire, to take up any quarrel. At a later period, however, during the ages of chivalry, the champion was a knight, who entered the lists on behalf of an injured lady, a child, or one incapable of self-defense. The word is also applied to one who earns, or claims, the preeminence in feats of physical prowess, or skill.
Entry from Everybody's Cyclopedia, 1912.