Randle Patrick McMurphy A manual laborer, gambler, carnival barker, Korean War hero with a dishonorable discharge, and con man admitted to the ward from Pendelton Prison Farm, diagnosed as a psychotic. Really not insane, he transforms the ward by teaching the other inmates to question arbitrary and repressive authority. Eventually lobotomized after attacking Nurse Ratched, he is killed in his sleep by Chief Bromden.
Nurse Ratched The "Big Nurse," and former Army nurse. She maintains order by exercising absolute authority over the hospital staff and its patients. McMurphy compares her techniques with the "brainwashing" used by the Communists during the Korean conflict.
Chief Bromden A towering man of mixed Native American and white heritage. He is diagnosed as an incurable paranoid-schizophrenic, and pretends to be deaf and mute in order to protect himself from the forces of the Combine, which he believes is a mechanized society intent on usurping freedom and individuality. The Chief is gradually rehabilitated by McMurphy and emerges as the real protagonist of the book at the conclusion. He suffocates McMurphy after Nurse Ratched has him lobotomized and escapes from the hospital.
Dale Harding A college-educated and effeminate man, who is psychologically "castrated" by his sexy wife and Nurse Ratched. Harding is an Acute patient, one who has voluntarily committed himself to the hospital.
Billy Bibbit A 31-year-old man dominated by his mother to the extent that he is still unmarried and a virgin. Bibbit is also a voluntarily committed Acute, despite the fact that his wrists reveal a previous suicide attempt.
Max Taber A rebellious patient whose presence on the ward preceded McMurphy's. He was released from the hospital after being made docile by electroshock therapy.
Scanlon The last of McMurphy's followers left on the ward, he assists in the Chief's escape after McMurphy's death.
Cheswick The first patient to adopt McMurphy's rebellious stance. After McMurphy begins to yield to authority, Cheswick drowns himself.
Martini A delusional man, who, nonetheless, learns to laugh at himself and the world around him.
Sefelt and Frederickson Both men are epileptics. Sefelt refuses to take his medicine because it causes his gums to rot and his teeth to fall out; Frederickson, on the other hand, takes double dosages.
Big George (Rub-a-Dub) A Scandinavian former seaman with a morbid fear of dirt. He is captain of the boat on the fishing trip, and his fear of an enema causes McMurphy and Chief to defend him against the African-American hospital aides.
The Lifeguard A former football player given to fits of violent behavior. Like McMurphy, his commitment is involuntary. He explains to McMurphy that they can only be released when Ratched signs their releases.
Tadem and Gregory Two Acutes who join McMurphy on the fishing excursion.
Pete Bancini A patient who, like McMurphy, avoided the controlling influence of the Combine, but suffers from brain damage.
Colonel Matterson A wheelchair-bound patient who raves continually in disconnected metaphors.
Ellis and Ruckly Two Acutes turned to Chronics after receiving too much electroshock. Ellis stands in a posture of a crucifixion against the ward walls.
Old Rawler A noisy patient in Disturbed. He bleeds to death after castrating himself.
Old Blastic A "vegetable" who dies in his sleep during Chief's hallucination of the Combine's mechanized butcher shop.
Doctor Spivey A morphine addict, chosen by Nurse Ratched to work on her ward because she can exploit his weakness and vulnerability. He nevertheless begins to assert himself after continued exposure to McMurphy's behavior.
Nurse with a Birthmark A perpetually frightened and attractive young nurse. She defends herself from perceived threats by McMurphy by protesting that she is a Catholic, indicating her sense of guilt and fear of sex.
Japanese Nurse The one example of a woman in the novel who mediates the two extremes of "ball-cutter" and whore. She disagrees with Nurse Ratched's methods.
The "Black Boys" (Washington, Warren, and Geever) Chosen by Nurse Ratched as orderlies because of their hostility and strength. They keep order on the ward mainly by threatening the patients and each other.
Mr. Turkle An elderly African-American night watchman who smokes marijuana. McMurphy bribes him to help arrange the novel's final party.
Candy Starr A prostitute from Portland with a "heart of gold." She is physically attractive and passive, and relieves Billy Bibbit of his virginity.
Sandy Gilfilliam Candy's older and less-physically attractive friend; comes with her to the party on the ward.
Captain Block Captain of the fishing boat stolen by the patients. His relationship with McMurphy is initially adversarial, but the two men wind up getting drunk together.