Royalty

King, "Your/His (Royal) Majesty"
Queen, "Your/Her (Royal) Majesty"
Prince, "Your (Royal) Highness/His (Royal) Highness"
Princess, "Your (Royal) Highness/Her (Royal) Highness"

Emperor, "Your/His (Imperial) Majesty"
Empress, "Your/Her (Imperial) Majesty"
Prince, "Your (Imperial) Highness/His (Imperial) Highness"
Princess, "Your (Imperial) Highness/Her (Imperial) Highness"



Nobility

Duke, "Your/His Grace"
Duchess, "Your Grace/Her Grace"
Marquis, "Your Honour/The Honourable"
Marquise, "Your Honour/The Honourable"
Earl/Count, "Your/His Excellency"
Countess, "Your/Her Excellency"
Viscount, "Your/His Excellency"
Viscountess, "Your/Her Excellency"
Baron, "Sir"
Baroness, "Lady"
Knight, "Sir"
Lady Knight, "Lady" or "Dame"
Ambassadors, "Your/His/Her Excellency"



The heir of a duchy, or the person next in line, may be referred to as a marquis or marquise. In the instance of a county, such a person may be referred to as a viscount or viscountess. The address of 'Earl' is also interchangeable with 'Count'.