Casting Your Canon

This is kind of a continuation of the last post. When I start a book, I usually have some actor or actress already in mind. Like Nicolas in this current book? I totally see him as Josh Hartnett. And Thomas? Oh, if I could only cast Neil Patrick Harris... *sigh* 

Anyway, I bring this up because it's yet another thing I wonder about. When my book is published, I have no idea what will happen. I really hope the one day it'll become a major blockbuster like the Hunger Games. 

But who would really get cast? Would I end up with the ones I always pictured? I hope yes, but I also hope no. Why? Because I'm wondering if there is one actor or actress who walks in and all of the sudden I gasp and realize this is it. This is the complete personification of my character.

Who do you cast in your headcanon?