Brilliant acting defined by one look

Brilliant Brittani of Rambling Film had this fabulous idea for a post and then Ruth of flixchatter followed up with her own awesome list. I love that they wrote posts on that - for me the most amazing thing an actor can do is make us see real emotions - disappear into character's state of mind, state of heart, state of soul. While it would probably be impossible for an actor to show this kind of authenticity through entire performance, the best of them can do that in brief moments, just in one look.