The Green Lantern Corps was created by the Guardians of the Universe as an intergalactic police force. The Guardians created the Green Lantern Corps to replace the Manhunter Robots as their force to maintain order in the universe. At least one Green Lantern is known to have gone rogue, Sinestro of Korugar; several of his fellow Corpsmen, including John Stewart, were called into action to strip Sinestro of his power ring, prompting the former Green Lantern to swear a blood oath against the Corps. The Green Lanterns have a legend that it's impossible to see the beginning of time.