What term describes a character or force in opposition to the protagonist?

The term that describes a character or force in opposition to the protagonist is "antagonist." The antagonist serves as a critical element in storytelling, creating conflict and challenges for the protagonist, who is the central character around whom the story revolves. This opposition can take many forms, such as another character, a group, or even an internal struggle within the protagonist. The presence of an antagonist is essential for highlighting the qualities and growth of the protagonist, as their journey often involves overcoming the obstacles posed by the antagonist.

Other terms in the options refer to different concepts in literature. A foil is a character that contrasts with the protagonist in ways that highlight particular traits, but it does not directly oppose the protagonist. A dynamic character is one that undergoes significant internal change throughout the story, rather than serving as an opposing force. Lastly, the protagonist itself is the main character whose journey is at the heart of the narrative.