Disney is famous for bringing fairy tales to life on the big screen, and most fairy tales are by nature made up of stock characters and archetypes. That's one of the ways they remain timeless as well as accessible to many different cultures.
Still, most Disney characters have names. It's awkward to call someone constantly by his or her title, so the nameless sea witch in Hans Christian Andersen's Little Mermaid becomes Ursula, just as the Little Mermaid becomes Ariel. A few of the characters have held onto their honorifics, though, but you might be surprised to learn that they too have real names.