You’d think the most famous man in Britain would have a simple ID card, right? Wrong. If you tried to find a "William Windsor" in a phone book or on a flight manifest, you might be looking for a while. Honestly, the question of what is Prince William's surname is way more of a headache than it should be.
It’s not just one name. It’s a shifting, evolving thing that depends entirely on where he is, who he’s talking to, and—believe it or not—what his dad is doing at the time.
The short answer (if you're in a hurry)
Technically, he doesn't really have one. When you are a Royal Highness (HRH), the rulebook says you don’t need a last name. You’re just William. But since the modern world requires forms and name tags, he basically "borrows" a surname from his official title. Right now? That’s Wales.
Why Mountbatten-Windsor is the "Official" Answer
If you look at the Royal Family's own website, they’ll tell you that the family name is Windsor. That started back in 1917 because King George V realized having a German-sounding name (Saxe-Coburg-Gotha) was a PR nightmare during World War I.
Fast forward to 1960. Queen Elizabeth II and Prince Philip wanted to mix things up. They decided that their direct descendants—the ones who aren't constantly using "Prince" or "Princess"—would use the hyphenated surname Mountbatten-Windsor.
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William has used this exactly once in a major public way. When he sued a French magazine years ago over some invasive photos, the legal paperwork listed him as Monsieur William Mountbatten-Windsor. Why? Because French courts don't care if you're a prince; they need a last name for the filing system.
The School and Military Alias: William Wales
This is where it gets kinda confusing for us regular people. For most of his life, William didn't go by Windsor. He went by William Wales.
His father, Charles, was the Prince of Wales for decades. So, when William joined the Royal Air Force or went to university, he just took "Wales" and used it as a surname. It was on his uniform. It was on his locker. It made him feel—at least a little bit—like one of the guys.
- In the Military: He was Flight Lieutenant William Wales.
- At School: He was simply William Wales to his classmates.
- His Kids: George, Charlotte, and Louis all used "Cambridge" as their surname at school when William was the Duke of Cambridge. Now that William is the Prince of Wales, the kids have switched to using "Wales" as their last name too.
Basically, the surname follows the title. It’s like a moving target.
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The Duke of Cambridge Era
Remember the royal wedding in 2011? The Queen made him the Duke of Cambridge. Suddenly, "Wales" didn't fit as well. For about a decade, if he needed to sign a guest book or register a business interest, he was effectively a Cambridge.
When Prince George started school at Thomas's Battersea, his backpack didn't say "George Windsor." It said George Cambridge. It sounds like a name from a 19th-century novel, but it served a practical purpose: it let a future king blend in (as much as a kid with a security detail can blend in) with other students.
Wait, so is it ever just "Windsor"?
Sorta, but not really for William. The "House of Windsor" is the dynasty name. You’ll see more distant cousins—the ones without the HRH title—using Windsor or Mountbatten-Windsor as a permanent, fixed last name. For William, it’s more like a fallback option he almost never uses.
The "No Surname" Tradition
Historically, kings and queens didn't have surnames because they were the only ones with their names. If you’re the only "William" running the country, you don’t need to be "William Smith." You’re just the King.
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Even today, William’s signature is just William. No last name. No flourish. Just the first name. When he eventually becomes King, he’ll likely sign documents as William R (the 'R' stands for Rex, which is Latin for King).
Actionable Takeaways for the Royal Fan
If you’re ever filling out a trivia card or writing a formal letter, keep these distinctions in mind:
- For formal/legal stuff: If you absolutely must use a surname, Mountbatten-Windsor is the technically correct family name for the Queen's descendants.
- For the kids: If you're talking about George, Charlotte, or Louis in their current school setting, they are the Wales children.
- The "House" vs. the "Name": Remember that the House of Windsor is the entity, while Mountbatten-Windsor is the personal surname.
If you’re tracking how royal titles change over time, the best thing to do is watch the official London Gazette. That’s where the "legal" name changes actually happen. It’s dry reading, but it’s the only way to stay 100% accurate when the titles start shifting after a coronation or a marriage. For now, just think of William as a man of many names, mostly depending on which part of the map his current title points to.