Despite presenting itself as an upbeat and straightforward superhero animated series in advance of its September 2006 debut, Legion of Super Heroes (officially unhyphenated) became a magnet for controversy among longtime fans of DC Comics animation. Announced in the wake of Justice League Unlimited's "Far From Home," a late-run episode guest-starring the Legion of Super-Heroes (with a hyphen) that ended with a time-travelling Supergirl joining the team, rumors persisted the episode was intended to be a backdoor pilot before executive meddling got in the way. Arguing to the contrary prior to, during and after Legion of Super Heroes' two-season run, producer James Tucker insisted the series began solely as an effort by Warner Bros. for content tying into 2006's Bryan Singer-directed Superman Returns.
Breaking from the long-running DC Animated Universe, elements from those earlier series managed to creep into the new production owing to Tucker's long history with them beginning with Superman: The Animated Series. These became most apparent in the second season, which Tucker would compare to the Legion's "Bronze Age" in contrast to the brighter "Silver Age" tone of the first season. To that end, the second season pushed the timeline forward several years to pit the Legion against Imperiex, a cosmic threat from the far-flung 41st Century. A surprising choice, but one justified through the character being a mix of heavy-hitter and relative blank slate. As it would turn out, Imperiex was never the desired choice for the season's primary antagonist, nor what the series ultimately ended up with as its "big bad."
Even a scant few years removed from his introduction in 2000's Superman #153 by Jeph Loeb, Mike McKone, Marlo Alquiza, Tanya Horie, Richard Horie and Comicraft, Imperiex was an obscure choice for LoSH. A history with the Man of Steel and major role in 2001's Our Worlds at War crossover however, set him up as a capable world-ending menace with room for development. Previewing the coming season at 2007's San Diego Comic-Con, Tucker described Imperiex's appeal coming in part from a lack of "baggage" a character like Darkseid carried, the latter having been a regular presence in DC animation last seen in 2006's Justice League Unlimited series finale. This enabled the freedom to alter Imperiex's backstory while permitting actor Phil Morris (no stranger to DC Comics series, both animated and live-action) to push the character in unexpected directions.
Contrary to his original Jack Kirby-esque comic design, Imperiex was unrelated to the Fourth World mythos, but with that seminal run rarely far from the minds of the Warner Bros. Animation crew his backstory was rewritten to link him to Apokolips. Drawing the Legion into the fight against him was Superman X, a clone from the 41st Century who'd traveled back in time to stop Imperiex's devastating conquest. The aggressive and suspicious Superman X found himself in regular conflict with stalwart Legionnaire Brainiac 5, believing the soft-spoken "smart kid" to be every bit as devious as his progenitor, the android villain Brainiac 1.0.
This would be borne out midway through the season in the December 1, 2007 episode "Message in a Bottle," with Brainiac 5 drawing upon his ancestor's code in search of a solution to restore the bottled Kryptonian city of Kandor. This episode was a watershed moment for LoSH. Minor references and nods to earlier DCAU series crept in -- a cameo by Booster Gold and his robot valet Skeets in models hearkening back to their JLU appearances and a DCAU-inspired Phantom Zone projector design, for example -- but here, Brainiac 1.0 was portrayed by Corey Burton, who'd taken on the role in Superman: The Animated Series and continued it through JLU's penultimate episode.
This reprisal almost didn't happen, with the prolific Burton (recently heard as Cad Bane on The Book of Boba Fett) noting shortly after the airing of "Message in a Bottle" on his now-defunct personal website he was brought in to record his dialogue during ADR sessions after the animation had already been completed. He was still flattered the production thought enough of his portrayal to bring him in, and he would recur in later episodes.
The corrupted Brainiac 5 overtook and destroyed Imperiex in the first part of the second season finale, "Dark Victory." The dispatching of Imperiex, who remained gone even after a reset in the second part, was a shocking twist and one perhaps not achievable with a better known villain like Darkseid in the role -- which, protestations to the contrary, was actually the intent all along. The 2020 Warner Archive release of the complete series on Blu-ray revealed in an audio commentary track over the two-part series finale with Tucker, director Brandon Vietti and actress Kari Wahlgren that they had planned to include Darkseid in the series until Warner Bros. forced the creative team to reconsider and settle on Imperiex.
Legion of Super Heroes became a casualty of the sale of the Kids WB! programming block to the 4Kids Entertainment in 2008, but speaking to CBR after the airing of "Dark Victory: Part Two" Tucker expressed a desire to revisit the series, suggesting a direct-to-video film. Although Legion of Super Heroes has been largely underappreciated and overlooked, it's still a worthy entry into the Warner Bros. Animation DC Comics library and worthy of reappraisal and rediscovery by fans of the Legion and the DC Animated Universe.