Sydney Lassick (Chicago, July 23, 1922 – Los Angeles, April 12, 2003) was an American character actor. He is primarily known for his portrayal of Charlie Cheswick, the fragile and anxious patient, in Miloš Forman's film *One Flew Over the Cuckoo's Nest* (1975). His performance contributed to the film's great success, which won the five major Academy Awards, and solidified his image as an actor specializing in eccentric, neurotic, or emotionally unstable characters. His career featured supporting roles in notable films, making him a recognizable face in American cinema of the 1970s and 1980s. His other significant works include Brian De Palma's *Carrie* (1976), as the teacher Mr. Fromm, and collaborations with Mel Brooks in *Silent Movie* (1976) and *History of the World, Part I* (1981). He also appeared in Steven Spielberg's *1941* (1979) and was active in numerous television productions, although he did not receive specific individual awards for his performances.