Sinestro (Mark Strong)

Thaal Sinestro is a former green lantern who was dishonorably discharged for abusing his power he is the archnemesis of Hal jordan  and founder of the yellow lantern corps he was once a anthropologist on his home planet of korugar one day a injured and under attack green lantern lent him his power ring to fight off the threat then asked for the ring back to heal himself but Sinestro refused and watched the alien die a slow and painful death than took his place in the green lantern corps he also secretly enslaved his people back on korugar when abin sur died and Hal Jordan took his place Sinestro traineeme one day hal Jordan found out what he was doing on korugar and Sinestro was put on trial and found guilty as punishment they stripped him of his power ring and banished him to the antimatter world of Qward there he forged a new yellow power ring fueled by fear rather than willpower and sought revenge on the guardians as his new yellow power ring was the only thing that could overpower the green power ring except for hal jordans thanks to his  immense personal willpower