The Horus name is one of a series of titles given to the Pharaoh (and the oldest title), given to him when he ascended the throne. It's the modern equivalent of "Her Royal Highness, Queen of Britain" or "His Royal Highness, the Prince of Wales."

You can read more about it here: [www.ancient-egypt.org]

It has its origin in the linking of the king to the god, Horus.
Commoners and others didn't have these names.