1950s were known as the Golden Age in the Comic history. After scripting great comics around superheroes like Flash, Green Lantern etc. during this age, DC went on to release an amalgamation of all these golden age superheroes called the Justice League of America. The Justice League of America, created by Gardner Fox was a successor to the Justice Society of America which was released during the golden age.
In the initial phases, the comic revolved around seven superheroes which were popular at the time - Superman , Batman, Aquaman, Flash, Green Lantern, Martian Manhunter and Wonder Woman. This was the most powerful superhero team in the world of DC Comics. Many superheroes have joined this premier team over all these years fighting off aliens, extra terrestrial being who have tried harming the people of Earth and innumerable supernatural threats. Sworn by oath as the stalwart protectors of the planet Earth, these mighty forces came together and became a premier superhero team!