Adherent and advocate are synonyms for protagonist. Opponent is the opposite of protagonist. We have given below a collection of synonyms for "protagonist".
The protagonist is the main character of the story. The protagonist makes the main decisions that affect the plot, primarily affecting the story and its movement, and is often the character who faces the most significant obstacles. For example, the protagonist in Charlotte's Web is Wilbur. In MacBeth, MacBeth is the protagonist.