Justice League is an American animated television series which ran from 2001 to 2004 on Cartoon Network. It is the last show to be set in the DC Animated Universe. 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 renamed Justice League Unlimited, and aired for an additional three seasons.
Animator Bruce Timm, who co-produced Batman: The Animated Series and Superman: The Animated Series in the 1990s became Executive Producer on an animated series focusing on the Justice League. The roster consisted of Batman, Superman, Wonder Woman, a Green Lantern (John Stewart), The Flash (Wally West), Martian Manhunter (J'onn J'ones), and Hawkgirl.
According to audio commentary on the DVD release of Season 2, the second season finale "Starcrossed" was expected to be the final episode of the series. However, in February 2004, Cartoon Network announced a follow-up series, Justice League Unlimited, which premiered on July 31, 2004 and featured a larger roster of characters.
Kevin Conroy reprised his voice role as Batman from Batman: The Animated Series (1992–1995), The New Batman Adventures (1997–1999), and Batman Beyond (1999–2001). Tim Daly, who voiced Superman in Superman: The Animated Series (1996–2000) was initially involved but was unable to continue his role due to involvement with The Fugitive (a short-lived remake of the original 1963 TV series), and was replaced by George Newbern. Superman was initially redesigned to have a bit of a squint to his eyes and slight wrinkles that was also meant to make him look older, in addition to having a noticeable shining streak to his hair; he was redesigned to appear larger in physical girth than in the previous series. Fans did not like the older appearance and in the second season the streak was toned down to the point of almost disappearing and the squint was removed, in essence reverting Superman to his earlier animated look. As an in-joke, Superman's season one facial designs are used for an older Jor-El in the Justice League Unlimited episode For the Man Who Has Everything.
Most of the characters retained their general comic book origins and continuity, with Wonder Woman being the notable exception. In the Justice League series continuity, the premiere story arc "Secret Origins" revises the plot of Diana's competition against her fellow Amazons to be the ambassador of peace to man's world, and she is referred to as a "rookie" superhero during her first encounter with the League. (Subsequent episodes touched on her attempts to adjust to her new world). In an interview segment on the Season One DVD, Bruce Timm stated that he initially ran into some legal issues in using the Wonder Woman character, but was adamant that she be used in the series. Additionally, the character of The Flash was portrayed as somewhat younger and significantly more brash than his comic book counterpart, taking on a number of personality traits of Plastic Man, who provides a similar comic relief function in the JLA comics. Major changes were also made to the Hawkgirl character. The character of Hawkgirl became romantically involved with the John Stewart Green Lantern as the series progressed. A romantic relationship between Batman and Wonder Woman was also "shown" (hinted at but never "official" unlike Hawkgirl/Green Lantern) by the show's creators, who disliked pairing Wonder Woman with Superman. Robin is not paired with Batman in this animated series like he was on Super Friends. Although the series itself is animated in traditional 2-dimensional style, the opening credits are rendered in 3D with toon shading. The intro is a "stock" intro used throughout the series until Justice League Unlimited premieres.
In January 2009, IGN named Justice League Unlimited as the 20th best animated television series of all time.