Released this past March, Batman V Superman: Dawn of Justice served as the true launching point for the DC Extended Universe (after the franchise kicked off in 2013's Man of Steel). The film had a lot on its plate, continuing the story of Clark Kent/Superman (Henry Cavill) while also introducing a handful of new characters that will be explored more in later installments. Among the high-profile additions were Bruce Wayne/Batman (Ben Affleck), Diana Prince/Wonder Woman (Gal Gadot), and villain Lex Luthor (Jesse Eisenberg).
The portrayals of both Batman and Wonder Woman ranked among the film's highlights, but director Zack Snyder's take on Superman's arch nemesis was criticized. A departure from the more reserved businessman that fans are familiar with, Eisenberg's Lex was seen by some as being closer in characterization to the Joker than Luthor. While the Oscar-nominated actor was certainly malicious at times (his line about mothers), his performance did come across as uneven, leaving room for improvement in upcoming projects. Eisenberg will get another shot to make a first impression very soon, as he's now part of the Justice League Part One ensemble.
While at the MCM London Comic-Con (hat tip CBM), Eisenberg confirmed he is locked in for Snyder's team-up film. At this point in time, however, even he is unsure of how large a role he'll play in the movie, telling the audience that he's "kind of in wait":
"They just started filming Justice League, so I'm kind of like waiting for my crack at it. I don't know what I'm allowed to say, because I feel like there's probably some drone following me from DC, and if I say anything wrong I get, you know, picked off. But yeah I think so, and I love it, and I love everybody who's in it. You know, it's a really talented group of people."
That Luthor is returning shouldn't come as a great surprise. Batman V Superman seemed to be setting up Lex's connections with possible Justice League villains. Upon exploring the fallen Kryptonian scout ship in Metropolis, Luthor learned of the ship's functions and recorded archive of alien worlds. A deleted scene from Dawn of Justice - dubbed "Communion" - featured the LexCorp head standing in the Kryptonian birthing matrix and having some kind of interaction with a being holding three boxes (presumably the mother boxes). When Batman confronts Luthor in prison at the end of the film, Lex repeatedly says that someone is coming to take over Earth, alluding to either Darkseid or the heavily-rumored Steppenwolf.
The bigger question is going to be how exactly Luthor factors into the story. Eisenberg's quote seems to imply that he won't have many scenes as Lex. With Justice League currently in production, the actor is still "waiting for my crack at it," meaning it's most likely a glorified cameo that will be shot later on. One possibility is that a member of the Justice League pays Luthor a visit in jail to interrogate him about what he knows of the arriving alien threat. That would probably be the most realistic way to incorporate the villain in Justice League. Much of the running time will be dedicated to assembling the team of heroes as they take on a potentially apocalyptic menace, so unless Luthor is donning his classic battle suit, he can't really hop into the action.
It will be interesting to see what measures (if any) the filmmakers take to ensure that the Lex is Justice League is better received than the one in Dawn of Justice. In the aftermath of Batman V Superman's less-than-expected box office haul, Warner Bros. is attempting to course correct their burgeoning franchise to ensure that the rest of their slate is high quality. Luthor is one of DC's premiere antagonists, so it stands reason to believe the studio has big plans for him down the line. The onus is on Snyder and screenwriter Chris Terrio to make Lex a compelling character this time around, guaranteeing viewers will be more excited to see him again.
Suicide Squad will hit theaters on August 5, 2016, followed by Wonder Woman on June 2, 2017; Justice League Part One on November 17, 2017; The Flash on March 16, 2018; Aquaman on July 27, 2018; an untitled DC Film on October 5, 2018; Shazam on April 5, 2019; Justice League Part Two on June 14, 2019; an untitled DC film on November 1, 2019; Cyborg on April 3, 2020; and Green Lantern Corps on July 24, 2020.