(Warning: the following contains discussion of, and comic-book SPOILERS related to, the classic DC villain Darkseid, who is currently heavily rumored to be appearing in the DCEU's upcoming 'Justice League' movies. As such, theoretical SPOILERS abound, so proceed with caution and all that...)
If the currently proliferating rumors are true - and since they're largely being spread by Batman v Superman: Dawn of Justice and Justice League director Zack Snyder himself, that seems likely - then it seems that the legendary DC villain himself will be arriving in the DC Extended Universe in the very near future. In fact, according to Snyder, we may have already seen some signs of Darkseid in Batman v Superman, as part of Cyborg's introduction.
The big question now, though?
Just Who is Darkseid, Anyway?
After all, outside of a relatively small number of animated appearances, Darkseid has made a surprisingly small impression on the world at large, with his central villainy in the comic-book world yet to be fully translated to the screen - meaning that it's entirely possible to have loved DC for decades without ever really having to engage with just who that glowing-eyed monster-man in the corner is.
Now, of course, with DC having gone through about seven thousand reboots over the years, exactly who Darkseid is has changed a fair bit, and may well change dramatically as he's adapted for the screen, so it's best to take what follows as more of a rough, relatively spoiler-free guide than an exhaustive history.
With that in mind, then, let's start at the beginning...
Darkseid is (Sort of) a God
Specifically, he's a New God, a.k.a. a member of the Jack Kirby-created pantheon of super-powered (and distinctly god-like) aliens from the planets New Genesis and Apokolips. Darkseid was once second in line to the throne of Apokolips, before ascending to the throne by straight-up murdering his older brother. And then both of his parents.
At which point...things kind of took a turn. Y'see:
Darkseid Wants to Remove All Free Will From the Universe
Specifically, he wants to rule...everything. Only without any of that 'potential for unrest'.
As a result, he has long been obsessed with a MacGuffin known as the 'Anti-Life Equation', a mathematical equation that theoretically gives its user power over all life - and the ability to shape the thoughts and feelings of every living being.
In other words, its like television, only without having to worry about ratings.
The thing is...
Darkseid is Willing to Kill Anyone Who Gets In His Way
Which, over the years, has put him at odds with his own family, the neighboring planet of New Genesis, and pretty much every superhero in existence. In part that's because he keeps messing with Earth (due to the belief that the Anti-Life Equation is partly to be found in the collective minds of humanity), but also because he keeps killing people dear to the Justice League. A particularly bloody moment came when he brutally killed close to half of Wonder Woman's Amazonian people, earning him her undying hatred.
In fact, he's so dastardly that...
Batman is Even Willing To Use a Gun To Stop Him
Yup, that's right, Darkseid's schemes are so dark and hideous that Batman was once forced to use an actual, factual gun to stop him. Which, in fairness, would be less of a big deal in the DCEU, seeing as Batman clearly has fewer qualms about that in Batman v Superman, but in the comic-books that's a big ol' deal.
In fairness to Bruce, though, Darkseid had just killed his own son, and was actively trying to corrupt every reality in existence, and had just kind of destroyed space-time. Which is the sort of thing that only makes sense with a couple of thousand pages of context, which we definitely don't have room for here.
The main takeaway from all of that, though?
Darkseid is Big, Bad, and Very, Very Dangerous
That, and the fact that his arrival in the DCEU will likely also mark the beginning of a whole lot of space-based adventure - and hopefully the arrival of the similarly cosmos-adventuring Green Lantern Corps.
Also, anyone want to bet that he now believes the secrets of the Anti-Life equation to be hidden in Lois Lane's DNA for some reason, thus explaining her Batman v Superman-teased importance?