We would watch a show with these actors called Dragoncats. Just sayin'.
We're not sure what to call these types of actors, but it's whatever the opposite of "muscle tone" is. Which is what makes it so fun to imagine them in the brawns, boobs, and blood world of Westeros. How would Zooey Deschanel conquer Yunkai? By having so much cute fun outside their gates that the Yunkish finally surrender just so they can get closer to the ultimate manic pixie dreamgirl. On the opposite end of the spectrum, we have Aubrey Plaza, whose sarcasm is cold enough to build a new Wall. Though, she would probably still mess with "you know nothing" Jon Snow, just to see him get flustered. Finally, we have Michael Cera, who is a really good Joffrey because at any moment he can display his immense talent for making people want to murder him (although now we love him because he let himself be an impaled douchebag in This Is The End.
Of course, knowing George R.R. Martin's sick sense of humor, these would be the only characters with no chance of dying.