During the 2016 New York Comic-Con panel for Marvel's Iron Fist TV series, a major announcement for The Defenders hit the floor: Sigourney Weaver has been officially announced as the yet-unnamed villainess who will take on the team of Iron Fist, Jessica Jones, Luke Cage and Daredevil in the first team-up feature for the Netflix Marvel superheroes. The series is currently in production, and will reportedly hit the streaming service sometime after the first season of Iron Fist.
There's no word yet on who Weaver is portraying in The Defenders, or what her role will be in the highly-anticipated miniseries event. You can watch an official video of Weaver joining her Defenders costars - Charlie Cox (Daredevil), Krysten Ritter (Jessica Jones), Mike Colter (Luke Cage) and Finn Jones (Iron Fist) - onstage at Iron Fist's NYCC panel, above.
As with The Avengers, where fans did not officially learn which villain the team would face or the identity of the alien foot-soldiers they would spend much of the film's finale battling until the film began to premiere around the world, very little has been revealed as to how the various Marvel Netflix series are meant to come together. Thus far, each show has focused on its own set of enemies, with character-crossovers being limited to good or neutral members of the supporting cast, though a minor henchman from Daredevil did eventually pop up in Luke Cage.
Still, no shortage of fan theories have emerged that could point to what may or may not be happening: The second half of Jessica Jones featured a subplot involving a biotechnology and chemical company involved in the manufacture of a drug-cocktail that could grant Captain America-style superhuman strength and reflexes to users (with mind-altering side-effects) and implied a connection between this and top-secret information being hidden away by Luke Cage's late wife Reva; which was in turn revealed to be connected to the experiments that gave Cage his bullet-proof skin in his own series.
Even still, it's not 100% clear how a vague "corporate superhuman-formula conspiracy" (which, while not likely connected, was also the main villain plot in the first season of Agents of S.H.I.E.L.D.) would impact Daredevil, who spent his first season combating a gentrification scheme hatched by The Kingpin and his second battling the undead ninjas of The Hand - whose vague plans involved making more undead ninjas and digging an enormous hole in the middle of Hell's Kitchen for yet-uknown reasons. On the other hand, it's notable that Matt Murdock and Jessica Jones both received their powers in (separate) accidents involving chemicals of unknown origin.
Daredevil season 1 & 2, Jessica Jones season 1, and Luke Cage season 1 are now available on Netflix. Iron Fist season 1 arrives on March 17th, 2017. The Defenders and The Punisher arrive in 2017. Release dates for Jessica Jones season 2 and Daredevil season 3 have not yet been announced.