Hal Jordan's enemies: Power Ring

Hal Jordan was merely an aircraft cleaner when Abin Sur crash landed into Earth-3's Coast City. Because he was weak-willed, he was chosen by the ring of Volthoom, and was easily tricked by Abin Sur to take the ring. Wielding it now causes him to feel immense physical and psychological pain.

Alternatively, it was revealed was that a man named Joseph Harrolds met a monk named Volthoom (who has never been shown, but has spoken on occasion), who gave Harrolds nearly limitless power in the form of a power battery and matching ring. Harrolds then took on the alter-ego of Power Ring and joined with four other super-powered beings who sought to conquer their Earth, and together formed the Crime Syndicate of America.