His first name hasn’t been very popular historically. In British history, there have only been 2 reigning monarchs with this name, and there hasn’t been any in a few recent centuries. The name Charles actually means 'free man', which is a quite suitable characteristic of this monarch. The second name of Prince of Wales was given to him as a tribute to his father, Prince Philip. He was called Arthur not after the mythical king, but to honor his grandfather (Elizabeth’s father), whose full name was Albert Frederick Arthur George. Finally, he took one more name – George – after his crowning.
Besides Charles, Elizabeth has three more children – Anne Elizabeth Alice Louise, Andrew Albert Christian Edward, and Edward Antony Richard Louis. The Queen named her daughter and second son in honor of her husband’s parents. Let us remind you that Prince Philip is an heir of two dynasties: Andrew of Greece and Denmark, and Alice, the niece of the Empress of Russia.