The Justice League has faced off against many fearsome foes over the years, but Prometheus is one of the few villains who managed to best the DC Universe's premier super-team singlehandedly. While his initial attack on the team was an astounding success, the menacing villain suffered a series of embarrassing defeats that almost made him the laughing stock of the DC Universe. Despite that, Prometheus rose again as a terrifying villain years later in one of the most infamous Justice League stories ever.
Created by Grant Morrison and Arnie Jorgensen in 1998's New Year's Evil: Prometheus #1, the masked villain was introduced to be something of an inverse to Batman and Green Lantern. The unnamed antagonist was the son of two notorious serial killers who cut a bloody, murderous path across the United States before being gunned down by the authorities before his eyes.
Traumatized by the experience and swearing revenge against all those that would pursue justice, the boy uses his parents' accumulated ill-gotten wealth from their multiple killing sprees to travel the world and receive masterclass training before discovering a reclusive monastic order within the Himalayas that worships evil itself. Learning that their monastery is secretly built within an alien spaceship with a portal to a pocket dimension, the young man kills the alien cult leader and gains access to the dimension while using his training and the advanced extraterrestrial technology to create his villainous persona as Prometheus.
In addition to a full arsenal of advanced gadgets and weapons, Prometheus possessed a helmet that recorded and analyzed the movements of anyone it encountered, including the Justice League, and develop combat strategies accordingly. Prometheus could download the data directly to his brain while wearing the helmet and had already used it to copy the techniques of the 30 greatest martial artists in the DCU -- including Batman and Lady Shiva. Using this helmet, Prometheus imitated an amateur superhero that had won a contest to join the Justice League for a day, murdering him and taking his place.
Prometheus was initially successful in singlehandedly taking down the Justice League with his recorded data but Catwoman -- who had secretly infiltrated the team separately -- was able to stop him with a well-placed crack of her bullwhip. A few years later, Prometheus' rematch against the team similarly went awry for the intimidating villain when Batman was able to override Prometheus' helmet with a new program left him paralyzed.
While the true Prometheus recovered, a replacement villain named Chad Graham replaced him; Graham had been Prometheus' secret apprentice. Initially presented as the same villain that had antagonized the Justice League, this character was established as a thoroughly incompetent version of the antagonist. After being soundly defeated by Green Arrow, Graham is approached by Hush but rejected for his embarrassing ineffectiveness, fully reducing this once-intimidating villain to a running joke.
At the start of James Robinson and Mauro Cascioli's Justice League: Cry for Justice, the creative team retconned the Prometheus that had appeared following his confrontation with Batman to be a new character named Chad Graham, who merely the original Prometheus' understudy. Having recovered his physical faculties, the annoyed original Prometheus murdered his one-time protege before turning his full attention to Green Arrow for defeating Graham. After maiming Roy Harper, Prometheus set off a bomb in Star City killing hundreds of civilians -- including Roy's young daughter. Despite escaping back to his pocket dimension, Green Arrow catches up to the villain and murders him while keeping his death a secret from his friends.
Although Cry for Justice is remembered more for Roy Harper's maiming than Prometheus' return, it still made re-established him as a serious villain. Following his return here, Prometheus popped up again after DC's New 52 reboot and appeared as a major Arrowverse villain on Arrow.
Prometheus was introduced as one of the greatest threats the Justice League had ever known before he was reduced to being a villain who was too pathetic to team up with Hush or stop individual heroes. Sensing the character's meteoric fall from grace, DC gave Prometheus a last hurrah as Green Arrow's most personal enemy yet, which caused Oliver Queen to cross the moral line and killing him as a final send-off to the devious, deadly antagonist. But in addition to rebuilding his supervillain credentials, this also made him a part of Green Arrow's rogues' gallery, which likely led to his Arrowverse debut.