It was always going to be Zod as the villain
Goyer: "It was always Zod. It was always Zod for two reasons. Chris [Nolan] and I wanted to make a science fiction film. We wanted to take Superman back to his roots and we wanted to come up with a threat. One of the things that always bothered me – and I adore the Donner films – was he goes into the Fortress Of Solitude and he just comes out in that costume and starts flying around. It’s one thing to emerge with these superpowers and another thing to possibly help people, but why put on a costume and make a public statement about it?
"I’m serious. The thinking behind this film was if he’s going to do that, his coming out [as Superman], if you will, has to be a really big event – it has to be something Earth-shattering. It always also bothered me that people glossed over the fact that he is an alien, and I had said to Chris Nolan early on that even if he had no superpowers, if the world found out he existed it would be the biggest story that happened in human history.
"That meant a first contact story and that lead us to Zod. Zod was also important because I wanted it to be a story about two fathers and Zod is a link back to his Kryptonian heritage, his lineage. Zod was at one time friends with Jor-El and so I wanted the fate of the world to rest on which heritage he was going to choose. We wanted to give him this Sophie’s Choice: you can have the human race or you can have the resurrected Krypton on Earth."