The Justice League just officially gained a new adversary and a matriarch.
Today, Warner Bros. released its 2017 preview press kit, which contains descriptions and cast lists for all of the company's 2017 movies. The entry for Justice League has all the usual suspects (Ben Affleck, Gal Gadot, Ezra Miller, etc) with two interesting additions. One of them was previously rumoured, the other just makes sense, but neither had been officially announced until now.
Those would be Connie Nielsen and Jesse Eisenberg.
Nielsen will make her first appearance in June's Wonder Woman as Queen Hippolyta, the leader of the Amazons and mother to Diana Prince, a.k.a. Wonder Woman. Eisenberg, of course, appeared in Batman v Superman: Dawn of Justice as Lex Luthor. He ended that film in prison, but not after starting some kind of sinister chain of events. That means, though director Zack Snyder was coy about it when we visited the set, Luthor's story will continue in Justice League.
As for how Nielsen's Hippolyta fits in, it's most likely in a flashback from the beginning of the film when we learn about the history of the mother boxes, but that's educated speculation.
Directed by Zack Snyder, Justice League is scheduled for release November 17.