Tim Blake Nelson, who played Dr. Samuel Sterns in The Incredible Hulk, told Ain’t It Cool News that the plan is for his character to become the villain The Leader in a possible sequel:
Quint: Great well what about a potential HULK sequel? Gale Anne Hurd’s been going around talking about how you might be The Leader and the main villain of the next one.
Tim Blake Nelson: That’s the plan. That’s what they tell me, but I don’t know when that’s happening or what the details are but I am eager to do it and I hear that’s in the works. I would tell you if I knew more, but I honestly don’t.
Quint: Yeah, but you haven’t played a comic-book villain yet right?
Tim Blake Nelson: No, but I had a great time doing HULK, so if they want me for HULK 2 I’m there, it certainly was the plan going into HULK 1. When I met with them they said this is where it’s headed so I’m eager to do it.
Source: Ain’t It Cool News