Estelle Louise Fletcher was an American actress. She is best known for her portrayal of the antagonist Nurse Ratched in the film One Flew Over the Cuckoo's Nest (1975), which earned her numerous accolades, including the Academy Award, BAFTA Award, and Golden Globe Award for Best Actress.

Nurse Ratched is a fictional character and the main antagonist of One Flew Over the Cuckoo's Nest, first featured in Ken Kesey's 1962 novel as well as the 1975 film adaptation. 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 institutional power and authority in bureaucracies such as the psychiatric treatment center in which the novel is set.