Nurse Ratched (also known as "Big Nurse") is a fictional character and the main antagonist of Ken Kesey's 1962 novel One Flew Over the Cuckoo's Nest, as well as the 1975 film. A cold, heartless tyrant, Nurse Ratched has become the stereotype of the nurse as a battleaxe. She has also become a popular metaphor for the corrupting influence of power and authority in bureaucracies such as the mental institution in which the novel is set.
Louise Fletcher won the Academy Award for Best Actress for her portrayal of Nurse Ratched in the film. The hairstyle for Nurse Ratched was created by Carrie White. Louise Fletcher has said that the hairstyle was "a symbol that life had stopped for her (Ratched) a long time ago".  Nurse Ratched was named the fifth-greatest villain in film history (and second-greatest villainess, behind only the Wicked Witch of the West) by the American Film Institute in their series 100 Years... 100 Heroes & Villains.
The role was turned down by Anne Bancroft, Angela Lansbury, Geraldine Page and Ellen Burstyn before Fletcher received it. Fletcher had only acted once in the 13 years before appearing in One Flew Over the Cuckoo's Nest. She was thought of for the role after Shelley Duvall was suggested for an alternative role and Milos Foreman saw Fletcher appear with her in Robert Altman's 'Thieves Like Us'. 
Fictional character history
Nurse Ratched is the head administrative nurse at the Salem, Oregon, State Hospital, a mental institution where she exercises near-absolute power over the patients' access to medications, privileges, and basic necessities such as food and toiletries. She capriciously revokes these privileges whenever a patient displeases her. Her superiors turn blind eyes because she maintains order, keeping the patients from acting out, either through antipsychotic and anticonvulsant drugs or her own brand of psychotherapy, which consists mostly of humiliating patients into doing her bidding.
When Randle McMurphy arrives at the hospital, however, he flouts her rules with impunity, and inspires other patients to follow. Her attempts to cow him into submission—at first with threats and mild punishments, then with shock therapy—are unsuccessful, serving only to fuel his defiance.
Eventually McMurphy sneaks his prostitute girlfriend into the asylum, and encourages her to relieve fellow patient Billy Bibbitt of his virginity. When she discovers what has happened, Ratched threatens to tell Billy's mother about the transgression. Frightened, Billy commits suicide. Enraged, McMurphy attacks Ratched and chokes her nearly to death.
In retribution, Ratched has McMurphy lobotomized. Chief Bromden, another patient and the narrator of the novel, later smothers McMurphy as a mercy killing. With McMurphy gone, Ratched's order is restored, but her power is gone; the patients no longer fear her, and her loud, authoritative voice is reduced to a thin whisper due to her confrontation with McMurphy.
Nurse Ratched is a recurring character in the ABC's "Once Upon a Time". She is portrayed by Ingrid Torrance and works for the Evil Queen as a nurse in the mental hospital in Storybrooke. Although she appears in several episodes, her name is first revealed in the fifth season premiere "The Dark Swan".