At one point there was a rumor saying Supergirl, Bizarro, and Brainiac would be involved in the Man of Steel sequel. Supposedly, Brainiac is after the same codex General Zod was after, and Supergirl. Brainiac supposedly creates Bizarro to go after Supergirl. (So the main villain will be Brainiac and Bizarro is his “dirty-work” guy) The issue with this rumor is that a sequel to MoS hasn’t even been green lit yet. Snyder and everyone else involved in the “sand-box” of the DC Universe is too busy with the solo films and Justice League.
Whether or not its true, a Man of Steel sequel is inevitable, no matter how long we have to wait. So I’ll be fan-casting major Superman characters. Like other fan-casts, I add on over time so be sure to check back!