Shazam (The Wizard)
Shazam, also known as Mamaragan, is the wizard who grants Billy Batson the power of the hero Shazam. He lives in the Rock of Eternity, a secret lair that is also the prison of the Seven Deadly Sins. After Billy inherits his powers, the wizard passes away. However, Billy has been known to be able to summon the spirit of the wizard for guidance and advice.
In the movie, Billy will probably gain his powers from the wizard in the same way — he will be magically transported to the Rock of Eternity and chosen to wield the mantle of Shazam because of the good inside of him.