We need to take this with a grain of salt, but a Twitter account by the name of Wayne Enterprises recently Tweeted that Warner Bros. has their eye on former Game of Thrones star Charles Dance for the role of Steppenwolf. The main villain has been confirmed to be the primary antagonist of Justice League, after being teased in a deleted scene that was released just after the theatrical release of Batman V Superman.
We know that Warner Bros. is doing a lot to try and make Justice League a very different movie than Batman V Superman, and one thing that will be very different is the villain of the movie.
Zack Snyder is currently hard at work and deep into production on Justice League, his follow up to Batman V Superman: Dawn of Justice.
Snyder was already neck deep in pre-production on the Justice League movie, and production dates had already been scheduled when the very poor reception to Batman V Superman surfaced.