Happy Xmas (War Is Over) John Lennon & Yoko Ono
This is the reason why we never hear the Royal family's last name.
Even thought how odd it is that we NEVER hear the surname of the Royal Family used?
Well the reason is because they don't have one!
Yep, Prince William, Prince Charles, Queen Elizabeth and the rest of the Royal family don't have a last name like the rest of us do.
Up until 1917 they didn't use a surname AT ALL but in that year they decided to adopt the name Windsor which is the name you may have heard used before.
However, when filling out legal documents such as marriage certificates, male members of the aristocracy can use the surname Mountbatten-Windsor and only applies to direct descendants of Her Majesty.
This is the surname thought to be used by Prince William on the day he married Kate Middleton.
But confusingly, sometimes the surname Wales has been used by William and Harry such as for military purposes.
Imagine if your surname was THAT confusing - it would make filling in forms a nightmare!