The Wizard

If you're going to tell Billy Batson's origin story, you can't do it without the Wizard, who is also known as Shazam (though in the New 52, his true name is Mamargan). Millenia ago, the Wizard used his mighty abilities to defend humanity, but eventually it came time to pass his powers to another. The first time he tried to do this, it didn't go well, and it resulted in the rise of Black Adam. No doubt we'll see that unfold in the Black Adam movie. In the present day, the Wizard selected Billy as his new successor, having the young boy brought to his lair, the Rock of Eternity. Thankfully, this time around the ancient being chose wisely, and Billy became a proper superhero. Usually after mystically empowering Billy, the Wizard either passes away or is killed, though he has occasionally aided the World's Mightiest Mortal from beyond the grave. So even if he bites the dust on the big screen, he could remain a integral character later in the movie and even a sequel.