Notable Green Lanterns of the former Corps have been: Abin Sur (the original Lantern who bestowed the ring to Hal Jordan), Katma Tui (wife of one-time Lantern Jon Stewart, later murdered), G'nort, a stupid dog-humanoid whose uncle gave him a GL ring so he could aparrently create giant green fire hydrants and get in everyone's way, Torquemada (sorcerer), Kilowog (former GL who turned into general handyman for the Justice League, killed by Parallax), Arisia (girl totally infatuated with Hal Jordan, prematurely aged herself using the ring, became a confused supermodel on Earth after the Corps was destroyed), and Stel (robotic GL, heroic who died and then was actually revived by the power of the ring, since he was essentially just software re-booted in his robotic body). Another notable GL was Sinestro, who ended up using his power to dominate his home planet and was therefore exiled by the Guardians to the antimatter planet of Qward, Oa's counterpart. He ended up developing with the Weaponers of Qward a ring capable of duplicating the Lantern power--but using a yellow frequency, a perfect counter to theirs.
Still another Green Lantern was the every-annoying and stupid haircut-wearing Guy Gardner.
Guy was originally a decent, mild-mannered guy who was actually supposed to have received Abin Sur's ring, but Hal Jordan turned out to be closer. Due to an accident that put Guy in a coma for a number of years, he emerged with a twisted and brutish personality. When the Guardians were desperate for a Lantern on Earth and Hal Jordan had refused to help them, they gave a ring to Guy. He has recently been stripped of that ring and after a short adventure of self-discovery is now a completely different, non-human superhero who co-owns a superhero-themed restaurant/bar.