Chief Bromden: Bromden suffers from paranoia and hallucinations and is the narrator of the story. He's been at the mental hospital longer then any other patient and has gone through several electroshock treatments. He pretends to be deaf and mute in the ward so the other patietns and the staff will leave him alone but his contact with McMurphy encourages him to start standing against nurse Ratched and talking again.
Randle McMurphy: McMurphy is a loud and outgoing gambler and con man who pretends to be mentally ill in order to live what he thought would be a more comfortable life in the ward. McMurphy repeatedly clashes with nurse Ratched, challenging her oppressive rule in the ward and encourages the other patients to stand against her. While at times it seems that McMurphy is only out for himself, In the end, McMurphy sacrifices his own sanity to give the other patients the courage to leave and break free of the wards oppression.
Nurse Ratched: Nurse Ratched is the head nurse and the main authority figure in this novel. She manipulates the other patients into fighting each other and controls them with the threat of dangerous therapies if they misbehave. She is seen by the patients as all-seeing, making them afraid to go against her, but McMurphy uses the same kinda of manipulation against her, rallying the patients against her even as she uses shame and guilt to force them baxck into submission. Her and McMurphys battle against each other is the main conflict in the novel.