4. Green Lantern - Robert Sean Leonard
I have no problem saying Robert Sean Leonard is better than his role on House. As we saw in Dead Poets Society and Swing Kids, Leonard's potential was really off the charts. He had spell-binding, natural performances in those films, and delivered them with promise that he'd stick around for a fantastic career. Of course, like Gosselaar, he didn't really do much afterwards, which makes him ripe for the picking for a then low-key character like Hal Jordan. Of course, if they wanted some racial diversity (and wanted to capitalize on a specific 90s rapper who was getting quite the fan-base), they could bring in the John Stewart Green Lantern, with who else but Will Smith taking the ring? Considering it would be his role from Independence Day with a green suit, people would certainly be lining up for that feature, don't you think?
Alternate: Will Smith