Everybody knows there's only one Green Lantern: Alan Scott, defender of Coast City. We're kidding. Alan Scott was the Golden Age Green Lantern, but his name was inherited by Hal Jordan in the Silver Age, whose title introduced the idea of the interstellar Green Lantern Corps - a sort of space police force, each of whose officers wield a powerful ring that lets them create anything they can imagine, and which they use to protect their own designated corners of the galaxy. After discovering the former protector of Earth Abin Ssur, Hal was endowed with the title of Green Lantern of Earth, and for many became the one character synonymous with said title. For many, but not for everyone. Besides the poor guy he inherited the role from, Hal Jordan isn't the only Green Lantern to patrol the stars over our little planet. In fact there's been something like a half dozen human Lanterns over the years, all of whom brought something new to the table. The cocky Guy Gardner was actually first in line to replace Abin Sur - it just so happened that Hal was closer. He was a back up Lantern for years, just in case anything happened to Hal, but tragedy befell Gardner himself as he was put in a coma for a year and came out...a little unstable. And douchey. When Guy was still comatose John Stewart was selected as Hal's new deputy, the first black Lantern and one who did things very different to his superior. His methods paid off, though, as he ended up becoming the first mortal Guardian Of The Universe (the Lantern's bosses, effectively). The first time Hal got replaced more permanently, however, was after he went nutso and tried to destroy half the galaxy. People don't tend to take kindly to that. A new Lantern was to be tapped, and that tapee was young Kyle Rayner. Initially criticised as DC attempting to jump on the early nineties bandwagon of rebellious, "radical" teens, the young and inexperienced Rayner was in fact an interesting choice of replacement for Hal Jordan, one who was much more fallible and relatable to readers. Which of course meant that he got replaced ASAP with the more traditionally heroic Hal when he got cured of his space madness and everybody conveniently forgot about it.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/