4. Parasite
Often artistically depicted as a pink humanoid figure, Parasite is a long-standing Superman villain with the ability to absorb the power and energy of a living life-form by coming into contact with it. This brings a great nemesis for Superman, who when wearing the cape and disguised as Clark Kent even, at both and all times, must keep a distance and be mindful of his proxemics when dealing with a tactile foe in the Parasite. His inclusion in a MoS sequel would give Superman an imposing physical threat where he must use his brains along with his brawn to defeat his parasitic enemy. While I do not think the Parasite could support an entire film as villain solo, I do believe he would be a great ancillary or secondary villain to be featured in the next MoS installment. Having done away with telling the origin in MoS, the sequel would be the perfect place to open with an already-established Superman taking on a lower-level thug-like villain like Parasite, less bent on world domination than with settling petty squabbles with street crime, would be a fantastic way to open a sequel, giving Kal-El the chance right out of the gate to show off his powers, as well as start the film on a high note with a Superman-Parasite throw down. The Parasite's comic book villainy also has often intersected with the heroics of Kal's cousin, Kara Zor-El, better known as Supergirl, who was glanced at through the MoS digital comic prequel, so if brought into a sequel, having a villain that can pose threats to, and has history with, both members of the House of El, could make for a calamitous MoS sequel where both cousins El must combat this common foe.