What Is Prince William's Last Name?

Prince William has access to many things that we mere mortals don’t, including but not limited to: castles, crowns, and a fleet of potentially inbred corgis. But one thing the rest of us do have that he doesn’t? A last name, apparently.

Prince William’s official full moniker is William Arthur Philip Louis, which we can all agree is literally just a bunch of first names strung together without a last name in sight. So, like…does he just not have a last name at all? It’s all very complicated, TBH, so we’re diving into a bunch of (somewhat archaic) royal rules to break it down for you.

Kay, so Prince William Wasn’t *Born* With a Last Name

We know this thanks to William’s birth certificate, which has a section for “name and surname.” Behold:

london, united kingdom july19 the birth certificate issued by the city of westminster following the birth of prince william on july 19, 1982 in london, england photo by anwar husseingetty images

Anwar Hussein//Getty Images

As you can see, the royals simply and quite casually put “His Royal Highness Prince William Arthur Philip Louis” in this section, ignoring the request for a last name entirely. Meanwhile, Charles listed his name as “His Royal Highness Prince Charles Philip Arthur George Prince of Wales”—because why stop at shoving the word “prince” in your name once when you can put it in there twice?

Please note that William’s full name has actually changed since his birth. Now that he’s the Duke of Cambridge (a title Queen Elizabeth gave him after his marriage to Kate Middleton), William goes by “His Royal Highness Prince William Arthur Philip Louis Duke of Cambridge,” which you can see on Princess Charlotte’s birth certificate:

london may 5 the birth certificate of princess charlotte of cambridge which was signed by her father, the duke of cambridge at kensington palace and witnessed by a registrar from westminster register office, on may 5, 2015 in london, england the duchess of cambridge gave birth to a daughter at 834am on may 2nd weighing 8lbs 3oz who will be fourth in line to the throne photo by john stillwell wpa poolgetty images

WPA Pool//Getty Images

William Has Been Known to Use the Last Name “Wales”

Not having a last name can get kinda awkward when you’re attempting to do stuff like join the army and attend school, so Prince William does have a couple of names at his disposal. While at school and while working in the Royal Navy, the Royal Air Force, and as an air ambulance pilot, Wills used the last name “Wales” thanks to his dad being the Prince of Wales. I think we can all agree that “William Wales” sounds both great and kinda hilarious, although FYI, when he was serving as a pilot, he went by the far more official “Flight Lieutenant Wales.”

dartmouth, united kingdom june 03 embargoed for publication in uk newspapers until 24 hours after create date and time prince william who holds the naval rank of sub lieutenant trains with the royal navy at britannia royal naval college on june 3, 2008 in dartmouth, england prince william is spending two months training with the royal navy to familiarise himself with its structures, capabilities and working conditions, and will spend time in the caribbean aboard hms iron duke photo by max mumbyindigogetty images

Max Mumby/Indigo//Getty Images

He’s Also Been Known to Use “Mountbatten-Windsor”

Back in 1960, the Queen and Prince Philip decided to give their untitled descendants (aka royals who don’t use “His/Her Royal Highness”) a special last name.

Per the royal family’s website:

“The Queen’s descendants, other than those with the style of Royal Highness and the title of Prince/Princess or female descendants who marry, would carry the name of Mountbatten-Windsor.”

This is why Prince Harry and Meghan Markle’s children use the last name Mountbatten-Windsor!

london, united kingdom may 03 embargoed for publication in uk newspapers until 24 hours after create date and time prince william, duke of cambridge in his role as commodore in chief, the royal navy submarine service attends a service to recognise fifty years of continuous deterrent at sea at westminster abbey on may 3, 2019 in london, england the duke of cambridge has been commodore in chief of the submarine service since 2006 photo by max mumbyindigogetty images

Max Mumby/Indigo//Getty Images

The royal website goes on to explain:

“For the most part, members of the Royal Family who are entitled to the style and dignity of HRH Prince or Princess do not need a surname, but if at any time any of them do need a surname (such as upon marriage), that surname is Mountbatten-Windsor.”

So where does the name come from? “Windsor” is the surname that George V gave his descendants before Elizabeth added “Mountbatten,” which is a shout-out to the last name of Prince Philip’s maternal grandparents.

Prince William doesn’t use “Mountbatten-Windsor” frequently, but he did use it when suing French magazine Closer for publishing topless photos of Kate. In the lawsuit (which they won!), Wills and Kate were referred to as “Monsieur et Madame Mountbatten-Windsor.”

FYI, William’s Kids Have a *Different* Last Name

Instead of going by “Mountbatten-Windsor,” George, Charlotte, and Louis use the last name “Cambridge” at school. Which is obviously a new level of complicated but also kinda makes sense since Wills and Kate are the Duke and Duchess of Cambridge and because we know Prince William used his dad’s title (Wales!) when he was in school.

topshot britains princess charlotte of cambridge, accompanied by her father, britains prince william, duke of cambridge, her mother, britains catherine, duchess of cambridge and brother, britains prince george of cambridge, arrives for her first day of school at thomass battersea in london on september 5, 2019 photo by aaron chown pool afp photo by aaron chownpoolafp via getty images

AARON CHOWN//Getty Images

So yeah, in conclusion, Prince William doesn’t have a last name, but when he wants one, he goes with “Wales” or “Mountbatten-Windsor,” and his kids are using “Cambridge.” Fin!

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