General terms:
* Antagonist: This is the most common and general term, referring to any character or force that opposes the protagonist.
* Opponent: This term is more neutral and can be used to describe any rival or adversary.
* Enemy: This term implies a stronger sense of hostility and conflict.
More specific terms:
* Villain: This term usually refers to a human antagonist who is morally evil or wicked.
* Nemesis: This term describes a powerful and recurring enemy who is specifically designed to challenge the protagonist.
* Foe: This term is similar to "enemy" but often implies a more personal or direct conflict.
* Adversary: This term implies a more formal or official opposition, such as in a legal or political context.
Beyond individuals:
* Obstacle: This term can be used to describe any force that hinders the hero's progress, including physical obstacles, societal norms, or internal conflicts.
* Challenge: This term describes any task or situation that tests the hero's abilities or forces them to grow.
For non-human entities:
* Force of nature: This describes natural phenomena like storms or earthquakes that oppose the hero.
* Evil entity: This describes supernatural beings like demons or monsters that threaten the hero.
The best term to use will depend on the specific context of the story and the nature of the conflict.