King Charles' surname is Mountbatten-Windsor.
This surname was adopted by Queen Elizabeth II and Prince Philip in 1960 for their children. It combines the surnames of their respective families: Mountbatten (Prince Philip's maternal family) and Windsor (the royal family's surname).
The surname Windsor was adopted by King George V in 1917, replacing the German surname Saxe-Coburg and Gotha during World War I.
While King Charles is officially known as Charles III, he uses the surname Mountbatten-Windsor for personal and official purposes.
It's important to note that royal children are not typically given surnames in the same way as commoners. They are usually referred to by their titles, like Prince George or Princess Charlotte. However, the surname Mountbatten-Windsor is used for official documents and legal purposes.
