McMurphy is definitely one of the most memorable. His rebellious nature and his attempts to break the rules of the mental hospital make him stand out. And Nurse Ratched too. She is the symbol of authority and control in the asylum.
McMurphy for sure. He brings a sense of life and chaos into the otherwise dull and controlled environment of the mental hospital. He's a character full of energy and defiance. Nurse Ratched is also very memorable. Her cold, calculating ways of maintaining order are both terrifying and fascinating. Also, Chief Bromden is memorable. His perspective as a patient who has been silent for a long time but then starts to open up because of McMurphy's influence is quite interesting.
McMurphy is the most prominent. He is the catalyst for change in the mental hospital. His wild and unruly behavior is a contrast to the docile patients. Nurse Ratched is unforgettable as well. She uses her power to keep the patients in line, and her character represents the system that McMurphy is fighting against. Additionally, Billy Bibbit is a memorable character. His relationship with McMurphy and his own struggle with his mother's overbearing influence and his own insecurities are really engaging.