Wizard of Oz

The Wizard of Oz is the leader of Emerald City and used to be the ruler of all of Oz. It's a role traditionally fulfilled by someone of royal blood.

History
As long as anyone could remember, Oz was ruled by the noble house of Oz. The current King would also be the Wizard, as all members of the royal house could do magic.

However, after Queen Ozma died, there was not one royal left to succeed her. That's when the Sisterhood of Witches decided to elect a new Wizard, this became Walsh.