Do you define a great actor by their body of work, or by a handful of scenes? By hours of film or split-seconds of brilliance? Robert De Niro has been in some great movies, but what makes them so memorable, in many cases, are brief moments where he does a few small things with a prop or an expresssion or a gesture -- and takes the movie away from his co-stars and directors to make it his. Here are the standout moments where De Niro truly shines.