Here's a leaked first look at Hal Jordan's Xudarian spiritual guide, Tomar-Re. In the comics, Tomar-Re was assigned to prevent the destruction of Krypton and to investigate a Green Lantern gone rogue. Potential spoilers!
Tomar-Re could play two major roles in the film. First off, in the comics, Tomar-Re is one of the Green Lantern's assigned to investigate reports that Hal Jordan's mentor Sinestro was running a dictatorship on his home planet Korguar. We know the Sinestro starts off as a hero in the film, so it's possible Tomar-Re could be the Green Lantern who spurs the Korugarian's villainous turn.
Also, Tomar is dead in the comics — this isn't a spoiler, as he's been dead for 20 years, ya poozers. Upon his death, his ring selected John Stewart as his successor. Nick Jones plays John Stewart in GL, so could we see him eventually inherit Tomar-Re's ring?