Nurse Ratched – The ward superintendent and ultimate authority. A handsome woman in her late forties/early fifties with an odd perfection about her -- a face smooth, calculated, and precision-made, like an expensive baby doll.
Chief Bromden - A large, bull-muscled Native American with schizophrenia. While he is a powerful man of six and a half feet, he thinks of himself as small. Through most of the action he pretends to be deaf and dumb.
Billy Bibbit - In age, thirty-one, but psychologically an adolescent still under his mother’s control. Billy has an extreme speech impediment (stutter).
Dale Harding – Age: 40 – 50, The most educated of the patients and their unofficial leader before McMurphy's arrival; a handsome, nervous effete man.
Charles Cheswick – Age: 30 – 40, A Patient, alternately truculent and cringing. Cheswick is always demanding change, but never has the courage to see anything through.
Anthony Martini – Age: 40, An eager and bright-eyed Italian who suffers from hallucinations.
Frank Sacanlon – Age: 45 – 50, A patient, obsessed with constructing bombs to blow up the world. Aside from McMurphy and Bromden, he is the only non-vegetative patient there by force.
Ruckley – Age: 40 – 50, A once powerful man, now blank-faced and empty-eyed, the result of a botched lobotomy. He spends most of the time crucified against a wall, occasionally screaming profanities.
Ellis – Age: 30 – 50, Once an "Acute" patient, now a "Chronic" in a vegetative state, the result of electroshock therapy.
Colonel Matterson – Age: 50 – 80, The oldest Chronic on the ward, a petrified cavalry soldier who cannot move without a wheelchair. He is given to lifting the skirts of passing nurses or teaching history out of the text of his left hand.
Jim Sefelt – Age: 40, An epileptic patient. He refuses to take his anti-seizure medication because he is afraid that his hair and teeth will fall out.
Bruce Fredrickson – Age: 40, An epileptic patient. He takes Sefelt's share of the medication because he is afraid of seizures.
Dr. Spivey – Age: 40, The resident psychiatrist, a harassed little fellow of no great force.
Nurse Flinn – A young (early twenties) nurse, eager but also apprehensive of the patients.
Aide Williams – Male or Female, 35-40, African-American, principal orderly in the ward, full of enough hate to be capable of performing Nurse Ratched's bidding with precision.
Aide Warren – Male or Female, 35-40, African-American, principal orderly in the ward, full of enough hate to be capable of performing Nurse Ratched's bidding with precision
Aide Turkle – 50 – 7-, An elderly kind man who works the late shift in the ward. He enjoys his liquor and marijuana.
Technician Aide Washington – A young female orderly in the ward.
Candy Starr – A young beautiful carefree prostitute and friend of McMurphy.
Sandra Gilfillian - Another young prostitute and friend of McMurphy.