There are a lot more ring-wielders than just Ryan Reynolds
Played by: Peter Sarsgaard ("An Education," "Jarhead")
Origins: Deviating from the comics, the film has Hammond a scientist (and friend of Hal Jordan's) who investigates the alien corpse of Abin Sur and is infected by the film's chief villain -- the enigmatic entity Parrallax -- which grants Hammond telepathy at a high cost.
Powers: Exposure to Parallax makes Hammond's head bigger, literally, and grants him powerful telekinetic abilities. He just can't wear very many hats.