Dr. Stockmann is the generous and optimistic medical officer for the town's lucrative new public baths. After suspecting the water is making tourists sick, he orders laboratory tests that confirm contamination from a nearby tannery. Believing the town will welcome his discovery and fix the issue, he prepares to publish his findings. He values truth and public health above economic convenience.

Peter is the town mayor and the primary administrative force behind the Kirsten Springs baths project. He represents the established institutional power of the community. Rigid and highly frugal, he prioritizes the town's economic success over his brother's alarming scientific findings.

Hovstad is the editor of the People's Daily Messenger, the local newspaper. He identifies as a political radical who opposes the wealthy elite running the town. When he learns of the contaminated water, he initially sees the scandal as a perfect opportunity to overthrow the local administration, though his dedication to these ideals faces intense economic pressure.

Catherine is Dr. Stockmann's pragmatic and caring wife. She manages the household and grounds her husband's lofty idealism with practical concerns about their family's security. While she supports his pursuit of truth, she becomes increasingly anxious about the social and financial backlash they face from the town authorities.

Kiil is Catherine's wealthy, elderly father. He is a cynical and miserly man who owns the tanneries located in Windmill Valley. Harboring old resentments against the town council, he initially finds the water contamination report amusing, assuming it is an elaborate prank to humiliate the mayor.

Captain Horster is a ship captain who has traveled the world. Unlike the other townsfolk, he remains largely apolitical and stays out of local disputes. However, his experiences abroad have instilled in him a strong belief in free speech, prompting him to support Dr. Stockmann's right to be heard.

Petra is the Stockmanns' adult daughter. She works as a teacher and holds progressive, independent views that often clash with the conservative values of the town. She is deeply loyal to her father and encourages him to stand firm in his convictions without compromising the truth.

Billing is a junior editor at the People's Daily Messenger. He frequently voices radical political opinions and eagerly anticipates the downfall of the town's conservative leadership. Despite his revolutionary posturing, he actively seeks a secure government position for himself.

Aslaksen is the printer and publisher for the local newspaper, as well as a representative of the town's small-property owners. He prides himself on being a reasonable, law-abiding citizen who strictly adheres to the principle of moderation. He uses his financial influence over the paper to ensure it never strays too far into controversy.

Ejlif is one of Dr. Stockmann and Catherine's young sons. He grows up in a warm, comfortable household that is quickly destabilized by the town's aggressive reaction to his father's scientific discovery.

Morten is the other young son of Dr. Stockmann and Catherine. Like his brother, he is an innocent bystander caught in the rapidly escalating conflict between his family and the community.