Once a relatively obscure villain within the DC Universe, Eclipso has become one of DC's most powerful magical characters. Once merely a man cursed by a black diamond, he was retconned into being a former servant of God and a dark predecessor to the Spectre. This more gruesome characterization made him stand out in the grim and gritty '90s.
Announced as the primary villain for Season 2 of Stargirl, Eclipso has a rather murderous history with several of the young heroes on the show. This took place during Eclipso's rise to fame in the '90s, where he waged war with the former leader of the Suicide Squad, Amanda Waller. Here's what makes Eclipso such a terrifying villain nearly three decades later.
The Darkness Within
"The Darkness Within" crossover in 1992 was written by Robert Loren Fleming and Keith Giffen, lasting twelve issues. It was revealed that the Eclipso entity was not simply a dark half of Bruce Gordon (whose name was a tongue in cheek reference to Bruce Wayne and Commissioner Gordon), but a dark spirit of vengeance that had actually possessed Gordon. Trapped on the Earth's moon due to the lunar nature of his powers, he begins to strike at the world at large, possessing heroes with his black diamond and creating monstrous beasts from their anger.
Eclipso also established that his years of being a low-rate supervillain were all a ruse to stay under the radar, with his newfound weariness for the facade explaining his all-out assault against the Earth. His plans of conquest nearly succeeded, resulting in his possession and absorption of powerful heroes such as Captain Marvel and even Superman. Ironically, it was the freed Bruce Gordon, who led a group armed with solar weapons, that played a key part in his defeat. The Will Payton Starman sacrificed himself to destroy Eclipso's moon base, scattering his diamond's shards across the Earth.
War of the Shadow Fighters
In the Eclipso ongoing series that came afterward, Eclipso had reconstituted himself and had taken over a volatile South American country. Cave Carson, Bruce Gordon and Gordon's fiance Mona Bennet were sent to investigate, which only led to Carson being brutally beaten. The Creeper also attempted to vex Eclipso, but to not much avail.
Robert Loren Fleming and Audwynn Jermaine Newman's Eclipso #11 saw Amanda Waller putting together a team of heroes to take down the villain. Waller was no longer in charge of the Suicide Squad, who had their own ongoing series brought to a close around that time. This new team was called the Shadow Fighters, and their ranks included the aforementioned Creeper, Peacemaker, the Beth Chapel version of Dr. Mid-Nite, Major Victory, Citizen Steel, the Yolanda Montez Wildcat, Manhunter and Nemesis. Despite their impressive combined power, only Nemesis survived this initial assault against the powerful villain. Though he was seemingly eviscerated in the fight, the difficult to kill Creeper would return later on down the line.
Nemesis would later be joined by the mystical Nightshade as well as Chunk, an associate of the Flash. They managed to escape Eclipso literally throwing a nuclear missile at them, with the villain having only grown angrier when Waller had the slaughtered Shadow Fighters' bodies retrieved.
A visit to the United Nations only further bolstered the fight against Eclipso, who was revealed to in fact be the time-traveling adult child of Bruce Gordon and his future wife Mona. The villain's then current conquest would finally be squelched when the supremely powerful Phantom Stranger reunited his diamond's shard, imprisoning him in the Heart of the Darkness. This would also bring the dissolution of the Shadow Fighters, who haven't reassembled since. Eclipso's kill count beforehand, however, was increasingly merciless, casually eliminating a number of heroes. These included the aforementioned Beth Chapel and Yolanda Montez, who are both characters on the Stargirl show. Though those versions are a good bit younger than they were in the comics, their days may still be numbered once Eclipso brings his dark magic to the series.