4. Green Lantern/Green Arrow
Green Lantern and Green Arrow share one of the most famous (and revered) team-ups in comics history. The dichotomy between the two heroes would be an incredibly interesting basis for a film, as Oliver Queen's vigilantism as the emerald archer meshes with Hal Jordan's job as a crime-fighting, law-enforcing member of the Green Lantern Corps. In the comic book run of their team-up (which began in 1970), the two stood for very different things. Oliver often demanded immediate, radical change, which contradicted Hal's ideals of working within the institutions of government and law. Oliver demanded social change, whereas Hal was determined to stop criminals. Each would find his personal beliefs challenged by the other, as the two traveled America in a beat-up pickup truck facing many social issues along the way. Though the cross-country social commentary may not go over well with modern audiences, the differing opinions of two superheroes who struggle to find ways of working together to make the world a better place could make for a great film, especially in the more "real world" conscious DCU that has been established thus far.