Batman the 6th said:
Wow this is all confusing. I thought the GL's were all on the same Earth, and that one gave it up, but there were still 2 of them with rings. Heres a question. How many heroes are there in DC comics? And how many are in JLU the cartoon. Is roster the only members of the team, or just the founding and main members? So only 1 other Superman survived, then died in IC. Kal-L and Kal-El were the only Supermen right? I still don't get it. Supergirl died in COIE's, yet she comes back later. I should buy the COIE's for 25 bucks to understand most of this.
A "quick" summation of Green Lantern history:
There have been five Green Lanterns from Earth, four of whom are part of the Green Lantern Corps. The first, Alan Scott, had a ring made of the magical emerald flame, though it served much the same purpose and use as the Oan power rings used by the Green Lantern Corps. After the death of Abin Sur, Hal Jordan was appointed Green Lantern of sector 2814 (Earth's sector). There was a period when the Guardians were dissatisfied with Hal Jordan, and appointed John Stewart the Green Lantern of sector 2814 (John is the Lantern in the Justice League/JLU series). After John Stewart retired, the Guardians appointed Hal Jordan's longtime companion Guy Gardner a Green lantern, saying that he was more worthy of the power ring than Jordan. This left sector 2814 with three green lanterns (Hal was referred to as 2814.1, John as 2814.2, and Guy as 2814.3. Alan Scott was given honorary membership into the Corps, but is not affiliated with them). After Hal Jordan's home city of Coast City was obliterated by Mongul and the insane Cyborg Superman, Hal Jordan lost his mind. After a reprimand from the Guardians, Hal went on the warpath to Oa, homeworld of the Lanterns, and killed many Green Lanterns along the way. Finally, Hal Jordan absorbed the power of the Central Power Batttery (the battery from which all Green Lanterns derive their power) and became the villain known as Parallax. Ganthet, the last surviving Guardian was empowered by the deaths of his brothers to find one last Green Lantern. That Lantern was Kyle Rayner, and Ganthet gave Kyle the last and most powerful Oan power ring. Kyle fought against Parallax many times, but eventually Parallax sacrificed himself in the event called Final Night in an attempt to reignite Earth's sun, an attempt that was successful. Hal Jordan then became the Spectre (the host to God's wrath on Earth), and Kyle set about reforming the Green Lantern Corps. Guy Gardner had been kicked out of the Green Lantern Corps for disobedience years before Jordan became Parallax, and John Stewart had been crippled in battle and surrended his ring because of it. Only recently, in the Green Lantern: Rebirth miniseries was Hal Jordan brought back to life, and John Stewart and Guy Gardner given power rings. Kyle Rayner also resurrected the Guardians of the Universe and reforged the Central Power Battery, paving the way for the newly resurgent Green Lantern Corps.
There are hundreds, maybe thousands of superheroes in the DC universe, but only a few ever join the prestigious Justice League of America. The lineup usually hovers around 7-20 members, with membership being expanded in times of crisis. The real rock of the Justice League is the Martian Manhunter, J'onn J'onzz, who has been with the League through all of its incarnations. Superman, Batman, and Wonder Woman are also longtime League members. The Justice League was formed by Superman, Batman, Wonder Woman, the Martian Manhunter, the Flash (Barry Allen), Green Lantern (Hal Jordan), Aquaman (Orin/Arthur Curry), and the Black Canary (Dinah Laurel Lance), with secret funding provided by Queen Industries (owned by Olliver Queen, the Green Arrow) and Wayne Enterprises.
Hope that helped you out!