Sydney Lassick (July 23, 1922 – April 12, 2003) was an American actor perhaps best known for his role as Charlie Cheswick in the feature film One Flew Over The Cuckoo's Nest. (His first name was sometimes spelled Sidney.)

He was born in Chicago, Illinois to Russian immigrants. He died at age 80 in Los Angeles, California from diabetes.

Was born to Russian immigrant parents.

Was best known for his role as "Charlie Cheswick" in One Flew Over the Cuckoo's Nest (1975).