While watching "One Flew Over the Cuckoo's Nest" recently for the first time (I know, I know...) I could not help but be inspired pretty much every part of the movie. Nicholson's performance is phenomenal and definitely deserving of the Academy Award for Actor in Lead Role for the year 1975. Also of note is that the film won a clean sweep of all five major awards that year (Best Picture, Actor in Lead Role, Actress in Lead Role, Director, Screenplay).
Anyway, I also could not ignore Nicholson's on-screen style. Something about it struck me as classic. Maybe because I could easily see a young man today wearing exactly the same thing. I've dissected Nicholson's outfit and have found modern examples of pieces that closely resemble his wardrobe in the film. Please also notice that Nicholson is not a waif-like model (nor has he ever been) in this film. He has a pretty filled out, normal body type.
So, top to bottom: