Before Batman v Superman: Dawn of Justice was even dreamt up at Warner Bros., Zack Snyder was trying to figure who the villain would be in the Man of Steel sequel.

"I remember talking about 'What's the next villain?'" Snyder recalled to Entertainment Weekly. "'We can't do another alien invasion.' Brianiac was definitely down the road. Metallo, I think, was going to be the main bad guy of this movie."

Metallo (also known as John Corben) is a nearly-invulnerable cyborg that uses Kryptonite as a power source.

The direction of the Man of Steel sequel changed drastically when Snyder made a suggestion at a meeting with screenwriter screenwriter David S. Goyer and executive producer Christopher Nolan (See, he is involved). "I said, 'What about at the end of the movie we do a scene where there's a crate full of Kryptonite delivered to Wayne Manor,'" Snyder remembered. "Everyone was like...'Okaay.' Once you say it out loud it's a problem because you can't unsay it."

That's the moment Batman v Superman was born. Luckily for Snyder, Henry Cavill doesn't mind sharing the superhero spotlight. "As far as the individual character is concerned, this is not a Superman sequel," Cavill explained. "It's more of an introduction to Batman, an opening to Justice League, and an expansion of the world that was created in Man of Steel."

In Batman v. Superman: Dawn of Justice, fearing the actions of a god-like Super Hero left unchecked, Gotham City’s own formidable, forceful vigilante takes on Metropolis’s most revered, modern-day savior, while the world wrestles with what sort of hero it really needs. And with Batman and Superman at war with one another, a new threat quickly arises, putting mankind in greater danger than it’s ever known before.

Batman v. Superman: Dawn of Justice opens March 25, 2016.