Without doing a search on the Internet...

[ignorantgenius]

...does anyone know what Prince William's surname is? Just curious as to how many people know this.

[ChuckFickens]

Mountbatten-Windsor (I didn't need to search as it came up in another thread on here recently)

[puzzled54]

Isn't it Windsor?

[Whickerman]

As he uses the title 'Prince' he does not use a surname other than (to this point) Wales. If he was any other male member of the family NOT using the title Prince it is apparentl Mountbatten-Windsor, per the Queens's request, although formally just Windsor

[saxy_jag]

His service ID badges refer to him as WIlliam Wales.

[beejaybee]

Until 1917 The British Royal family were known as Saxe-Coburg-Gotha. A bit of useless info.

[milly143]

He actually doesn't have a surname but for any purpose if him needing one for some reason it's Mountbatton-Windsor. Although on his RAF uniform his name badge says Wales. And I know that because I was the one that started the thread asking about it recently.

[ABerrant]

BTW "Wales" is no longer a viable style for the newly created Duke of Cambridge.

[atalanta]

Rather a long while ago, the queen decreed that her male descendants would bear the surname "Windsor" and the female ones would be "Mountbatten-Windsor". I do not know if this has been changed.