Books With Royalty?

I need a favor from my wonderful readers for an upcoming feature on the blog.

What are some of your favorite books with royalty in them? The royalty could be fictional (think The Princess Diaries by Meg Cabot), or real (The Other Boleyn Girl by Philippa Gregory). They don’t necessarily have to be YA either, though if they were, that would be a bonus.

I need some suggestions, cause I’ve wracked my brain and checked out Goodreads, and I haven’t come up with much.