Justice League is an American animated television series which ran from 2001 to 2004 on Cartoon Network. It is part of the DC animated universe. The show was produced by Warner Bros. Animation. It is based on the Justice League of America and associated comic book characters published by DC Comics. After the second season, the series was replaced by Justice League Unlimited, a successor series which aired for three seasons.
As alien invaders (based loosely on the White Martians from DC Comics) who were accidentally awakened on Mars begin to take over the Earth, Superman and Batman rescue J’onn J’onzz who telepathically summons Wonder Woman, Hawkgirl, the Flash, and Green Lantern to defeat the invasion. Superman gathers everyone at the newly built Watchtower funded by Batman (through Wayne Aerospace’s R&D budget) and asks to be part of a team, which he dubs the Justice League.