Based on Batman’s “Knightmare” in Batman v Superman: Dawn of Justice, it looked like the villain of Justice League: Part One would be Darkseid or possibly even Superman. However, a new report from Birth.Movies.Death. says that neither of these big names will be the big bad of the first Justice League movie. Instead, they claim that we’ve already seen the villain, albeit in a deleted scene that made almost no sense:
As BMD points out, Steppenwolf is a fairly blank slate, so there’s a lot that Zack Snyder could do with the character while keeping his hands off more popular DC supervillains. As long as Steppenwolf has interesting motivations, I’m curious to see what the character does, but hopefully his motives and range of knowledge will be more specified than Lex Luthor’s in BvS. Snyder has a long way to go in cleaning up the damage he did with Batman v Superman, and so hopefully Steppenwolf is a step in the right direction.
BMD also says that Darkseid will make an appearance in Justice League: Part One, but it will be at the end of the movie. Additionally, “The other DC solo movies between Justice League and Justice League 2 take place in realish time – ie, The Flash takes place after Justice League – so whatever evil plan Darkseid has will wait until Justice League 2 to be revealed.”
via Collider