One princess series that I love is Patricia Wrede's Dealing with Dragons
Cimorene, the princess, is talking to the dragon Kuzul.
"...you wouldn't have had any use for a princess if you the Queen of the Dragons, and if you hadn't decided to take me on, that yellow-green dragon Moranz would probably have eaten me," Cimorene explained.
"You mean, if I were King of the Dragons," Kazul corrected her. "Queen of the Dragons is a dull job."
"But you're female!" Cimorene said. "If you'd carried Colin's Stone from the Ford of Whispering Snakes to the Vanishing Mountain, you'd have had to be a queen, wouldn't you?"
"No, of course not," Kazul said. "Queen of the Dragons is a totally different job from King, and it's not one I'm particularly interested in. Most people aren't. I think the position's been vacant since Oraun tore his wing and had to retire."
"But King Tokoz is a male dragon!" Cimorene said, then frowned. "Isn't he?"
"Yes, yes, but that has nothing to do with it," Kazul said a little testily. "'King' is the name of the job. It doesn't matter who holds it."
Cimorene stopped and thought for a moment. "You mean that dragons don't care whether their king is male or female; the title is the same no matter who the ruler is."
"That's right. We like to keep things simple."