10. Sinestro
The Green Lantern movie was pretty bad, if we're honest - even if you were to disregard the source material and accept it as a standalone movie it still has very few redeeming features. However, one of the redeeming features it did have was the character of Sinestro. Sinestro was by far the most interesting and best-portrayed character in the movie and, if the post-credits scene was anything to go by (in which Sinestro donned a yellow power ring of fear), there was a suggestion that a spin-off movie/sequel was being considered (prior to the movie being received so badly). But I think it should still be something they go ahead with. The movie could explore Sinestro's past and what makes him so suitable for a ring that is powered by the ability to instil fear in people. Seeing him recruit for a brand new Lantern Corps - his Sinestro Corps, as they are known in the comics - would be great and the introduction of some of the horrible members (such as Karu-Sil, a savage raised by animals, Bedovian, a hermit-crab like cannibal, Devildog, a convicted murderer on at least 17 planets and Kryb, a hag who kills Green Lanterns who are parents and stores their children in a cage growing out of her back) would make for a devilishly dark movie.