Melisandra
The Red Woman looks a lot less terrifying out of costume. We’ve seen what the priestess is capable of doing (like convincing a man to burn his own daughter or bringing Jon Snow back to life) so we know just how dangerous that smirk can be. In real life though, Carice van Houten is as sweet and down to earth as it gets.
Van Houten notably refuses to live in Hollywood, saying that living in Europe is much more her lifestyle. Despite her sweet personality, she tends to take on darker characters.