Your Highness
Many forms of honorifics are for members of the nobility, clergy, military/naval forces, or royalty, mostly in countries that are monarchies. These include "Your Majesty", "Your Royal Highness" or simply "Your Highness", which are used to address certain members of royalty and "My lord/lady" or "Your Lordship/Ladyship" to address a peer other than a Duke, who is referred to as "Your Grace".