I can think of many classic movie scenes that deserve mention in the discussion, but I can think of none as deserving of the title “most iconic” as the shower scene in Alfred Hitchcock’s Psycho (1960). It’s the kind of scene that transcends the film itself. People who may never have seen the movie are still aware of it through film spoofs (High Anxiety) and other pop-culture exchanges . . .
I came across this video (below) by film editor Brian Carroll which combines archival interview footage from Hitchcock and Janet Leigh with film scenes and ties it to a modern soundtrack to great artistic effect. Worth your 4:30 if you are time-wasting. I think it makes a strong case for Psycho.
“I have always been fascinated with Hitchcock’s shower scene in Psycho. I remember the first time I digitized it years ago and went through frame by frame to deconstruct how exactly it was put together…
Out of all of Hitchcock’s films, this scene is the most scrutinized due to it’s nature of a young woman being viciously stabbed to death while in a very vulnerable position. In the year 1960, this was truly a groundbreaking moment in film. Without showing any nudity or actual stabs of the knife, Hitchcock crafted one of the most terrifying scenes in film history.” – Brian Carroll