What is a prime example of a supporting actor/character "stealing" the movie?

I often find that in some reviews that some critics/reviewers will go as far to say that one actor "steals the movie" meaning that this supporting character shines brighter than the rest of the cast despite limited attention or screen time. He or she may make a lasting impact on the audience, more so than the leads. Whether its adding some much needed humor to a story or by playing a wise mentor that helps our lead protagonist on their way. I also may add that it could be a character and not an actor meaning that it could be a CGI character like Groot from Guardians of the Galaxy. It doesn't necessarily have to be an actor.What do you feel is the best example of this? via /r/movies http://ift.tt/2AcQ9kL