What is King's last name?

What Is King Charles’ Last Name?

When you hear “King Charles,” you might wonder—what’s his last name? The answer isn’t as straightforward as it seems. Officially, the British monarch doesn’t need a surname, but when one is required, the King uses Mountbatten-Windsor.

The “Windsor” part traces back to 1917, when King George V changed the royal family’s name from the German-sounding Saxe-Coburg and Gotha to Windsor, distancing the monarchy from its German roots during World War I. That name stuck, becoming synonymous with the modern British royal house.

But where does “Mountbatten” come in? That’s from King Charles’ father, Prince Philip. Before marrying Queen Elizabeth II, Philip was a prince of Greece and Denmark, but upon becoming a naturalised British subject, he adopted the anglicised surname Mountbatten. When it came time to decide on a surname for the royal descendants, a compromise was reached: future generations of royals, including King Charles, would carry the double-barrelled Mountbatten-Windsor.

So while you won’t hear “Charles Mountbatten-Windsor” in official proclamations—the monarch is usually referred to by title rather than full name—the surname is used in legal and formal contexts, like on passports or military documents. Even members of the royal family without titles, such as the children of Princess Anne, use this name when needed.

In essence, the King’s “last name” is a quiet blend of tradition and personal history—a nod to both the institution of the monarchy and the man behind the crown.