Last week, a report surfaced broke that Marvel Studios may have a Dark Avengers film in development, with a completed script by an unnamed screenwriter. While the future of the MCU following next year's Avengers 4 is still largely unclear, the possibility of a villainous inversion of Marvel's premier superteam certainly offers an intriguing thought about where the cinematic universe could go next. That having been said, the MCU's various original series on Netflix may have already been quietly laying the foundation for their own supervillain ensemble to possibly team up and take on the Defenders.
As opposed to the films of the MCU, which have a habit of killing off many of their principal antagonists, the Marvel Netflix series has retained the majority of their villains, leaving open the possibility of them returning in the future. And, just like the comic book incarnation of the Dark Avengers, these Dark Defenders would be familiar faces with similar power sets to their heroic counterparts, setting up a climactic battle between both teams with all the street-level heroes facing each other's villains after seasons of escalating grudges.
Bullseye has been one of Daredevil's greatest enemies as much as the Kingpin since his creation in 1976's Daredevil #131 written by Marv Wolfman and illustrated by John Romita, Sr. Responsible for the deaths of Elektra and Karen Page, the uncanny marksman with the superhuman ability to throw any object with lethal accuracy and force quickly became one of Matt Murdock's most personal foes, and even masqueraded as Hawkeye as part of the Dark Avengers for a time.
With Wilson Bethel confirmed to be playing Bullseye in the third season of Daredevil, the new villain of Hell's Kitchen could be part of an ensemble organized and financed by Wilson Fisk to root out the Man Without Fear and his allies for good. Additionally, as he did in the comics, the villain will impersonate Daredevil to discredit the Devil of Hell's Kitchen in the eyes of the authorities and general public. Hold they decide to make their play even bigger, the nefarious duo would certainly not be at a loss of potential recruits to enlist in their sinister crusade.
Both of Luke Cage's principal antagonists, Season 1's Diamondback and Season 2's Bushmaster, have survived, and are thus set up for possible returns to Harlem. Given that Mustafa Shakir's Bushmaster can stand toe-to-toe with Cage without the use of a powered exosuit like Diamondback (not to mention receiving a better fan response), he's the more likely to return from his Jamaican exile, though Cage's half-brother could resurface, even without the technological enhancement, given the personal nature of his connection to the Hero of Harlem.