At the Warner Bros. panel at Comic-Con in San Diego today, director Bryan Singer said that he was in talks with the studio about a sequel to Superman Returns. He hadn't concluded a deal to do it yet, which he said is always "iffy," but he has every intention to do a sequel for 2009, and said that while Superman Returns reintroduced the character for new people, the next one will let him get all "Wrath of Khan on it." He added that you can expect an alien villain in the sequel.
He also joked that he has to see who's left in the cast if he ever were to return to the "X-Men" franchise. Ironically, right before being asked about it, he had been joined on the dias by original Superman director Richard Donner, whose wife Lauren Shuler Donner produced the first two "X-Men" movies.
In Star Trek II Khan came back with only one thing on his mind, hurting james kirk, and what a great film it was, but that quote by bryan is kinda worrying, it pretty much confirms Zod will be returning to hurt superman, then again him saying alien villian may mean someone else.
Darkseid, Mongul, Brainiac.