Although details on whom he'll be playing are scarce, Dafoe will apparently be a main character in the movie — alongside Batman, Superman, Flash, Wonder Woman, Aquaman and Cyborg — and will be around for both Justice League - Part 1 and Justice League - Part 2. The films, much like Marvel's Avengers series, will pit all of the DC superheroes against an unidentified, supervillain.
Although Warner Bros. has been pretty secretive about who the baddie will be, Snyder has hinted at Darkseid in Batman v Superman: Dawn of Justice and in a deleted scene that was published on YouTube by the studio. Neither Snyder nor Warner Bros. commented on whether Darkseid would be in the film, but all signs point to yes.
Dafoe isn't new to the superhero genre, either. He played Green Goblin in all three original Spider-Man movies directed by Sam Raimi and has done other work within the genre field. He also voiced the character Nathan Dawkins in Quantic Dream's Beyond: Two Souls game.
Justice League — Part 1, which will mark the end of DC and Warner Bros.' first cinematic universe phase, will star Ben Affleck, Henry Cavill, Gal Gadot, Ezra Miller, Jay Fisher and Jason Momoa. The film is scheduled to be released Nov. 17, 2017.