It takes a lot to bring a group of superheroes together. In Batman v Superman: Dawn of Justice, Superman and Batman resolved their differences just in time to team up against Doomsday, and Wonder Woman jumped into the fight shortly afterwards. In Justice League, Aquaman, Flash and Cyborg will be recruited to help battle Steppenwolf and his Parademon army. Of course, longtime comic book fans know that Steppenwolf serves Darkseid, and Justice League might make it quite clear that the ruler of Apokolips is looming in the shadows.
A new Justice League synopsis has surfaced online from FXXX Magazine (via Comicbook.com), much of which has information we already know. Batman will form a team of crimefighters to keep the world safe, and their first big opponent will be Steppenwolf. But the last sentence of the synopsis specifically states that Steppenwolf has been "charged" by Darkseid to hunt down three artifacts, which we already know to be three Mother Boxes. This is the first time that Darkseid has actually been named in a synopsis, making it clear to non-comic books fans that Steppenwolf isn't the one in charge on Apokolips.
So what does this mean for Justice League? Well, since Steppenwolf will be the movie's main antagonist, fans shouldn't get their hopes up about seeing Darkseid in action. However, he could stil be mentioned at some point, letting Earth's heroes know that there's an even worse threat out in the cosmos. Hell, we may even see Darkseid pop up briefly. It was reported last year that there will be a flashback scene in Justice League showing Darkseid's invasion of Earth thousands of years ago, subsequently leading to the humans, Amazons and Atlanteans hiding the Mother Boxes. If that doesn't happen, maybe we'll see him appear towards the end of Justice League to foreshadow that he will be a future adversary, similar to Thanos in The Avengers.
Darkseid's existence in the DC Extended Universe was revealed in Batman v Superman: Dawn of Justice when Bruce Wayne had a Knightmare where he was a resistance fighter on an Earth taken over by a rogue Superman in the future. The giant Omega symbol burned into the ground and the Parademons flying around confirmed that Superman had help from Apokolips, although only hardcore comic book fans understood the full implications of that vision. Even though Darkseid won't be at the forefront in Justice League, since he appears to be the DCEU's overarching evildoer, there's a strong chance he'll end up being the main villain in Justice League 2 (which currently doesn't have a release date). Eventually DC's main superhero team will have to face off against him like their comic book counterparts have on many occasions; the question is when.
Justice League hits theaters on November 17.