Dustin Hoffman in this...
I'm not positive, but think this is his first movie after The Graduate. I cannot imagine how audiences reacted to seeing him in this after playing an academically brilliant, but socially dumb 21 year old Southern California WASP ( that looked more Jewish than WASP'Y,) and then playing a prematurely aged 30-something Italian street hustler in this just 2 years later.
No other actor has ever been more versatile. Even Robert Duvall and Gene Hackman have been, but their appearances always remain the same.