You are so right Jan; it is a credit to Chris to be able to convey many different characters with just a look or stance and occasionally the costume plays a part, but mainly its just HIM.
You can usually pinpoint a character by a mannerism - without necessarily looking at hair-era type clues
When people ask me what I find so fascinating about Mr P, I usually tell them that he just has that ability to keep your interest focused on him on the screen; he really has an aura about him - he captures you and he has the great talent of saying many many things with just a look or holding his head a certain way. I can't say that about many actors. And let's not forget the voice!!!