The DC Comics Extended Universe kicked into high gear with the formation of its premiere super team in 2017's Justice League. The film pitted the League against Steppenwolf. He was clearly working for someone else, but the only hint was him mentioning "Darkseid" once. Darkseid, of course, in the comics is the head of the planet Apokolips and the main villain of the New Gods in Jack Kirby's acclaimed "Fourth World Saga" (Steppenwolf is his uncle). Darkseid was the first villain that the Justice League faced in their New 52's origin and it is likely that he will be connected to the Justice League for the rest of his comic book career.
The success of Avengers: Infinity War shows how smart it is to have your heroes face off against a cosmic threat and so the DCEU will likely make Darkseid as big of a part of their universe as the Marvel Cinematic Universe has done with Thanos. However, once Darkseid is finished, the DCEU will need to look elsewhere for threats and we have 20 possible cosmic-level villains who could work well for future film threats in the DCEU. Note that since we're not counting Darkseid, we are also eliminating villains connected to him, like Granny Goodness and DeSaad.
If there was a betting parlor that took bets on what villain would be the next major cosmic threat to show up in the DCEU following Darkseid, the odds would be very much in favor of Brainiac. The classic Superman villain is an obvious choice to be one of the next villains, likely in whatever the next Superman film is that comes out.
Brainiac debuted in the late 1950s, when the idea of a computer-like brain was still novel.
He actually shared the name with a kids "build your own computer" toy of the era. The company threatened to sue DC Comics, but the whole thing was settled with DC just giving them some free ad space for their toy. Brainiac's biggest move over the years was to shrink cities down and steal them. He did this to the Kryptonian city of Kandor. Working Brainiac into a new film could also involve introducing Kandor, which might also be a way to introduce Supergirl into the DCEU, as perhaps in this version of continuity, she could be one of the residents of Kandor. You probably don't want too many Kryptonian survivors out there, so it makes sense to consolidate them a bit.
The first attempt to create the DCEU came in 2011 when DC Entertainment released Green Lantern. The film featured the great Angela Bassett as Amanda Waller. The idea was that Waller would serve as the Nick Fury of the DCEU, as she would crop up in the other films that would follow, before they slowly all got tied together in the Justice League. Green Lantern was a relative flop, though, so the DCEU did not actually start until 2013's Man of Steel. Waller was recast in 2016's Suicide Squad with Viola Davis, so clearly the entire Green Lantern film has been wiped from continuity.
Therefore, the main villain of that movie, the yellow fear entity known as Parallax, could be used again, only this time against the rest of the DCEU. An interesting aspect of Parallax is that the character was shown to possess Green Lanterns in the comic books. Therefore, a possessed Green Lantern could be the reason why no Green Lantern showed up to help the Justice League in their battle against Steppenwolf. So the films could have the heroes face off against a Green Lantern possessed by Parallax. They can then free the Green Lantern, defeat Parallax and have a whole new Green Lantern movie set up for the future.
18 SINESTRO CORPS
Not only was the 2011 Green Lantern intended to be the start of the DCEU, it was also clearly intended to be the start of a series of Green Lantern films. The most obvious part where the studio's intentions were made clear was its usage of Sinestro. In the film, he is one of the Green Lanterns who helps Hal Jordan defeat Parallax. He is just an outright hero in the film. Obviously, we all know that Sinestro becomes so obsessed with order that he breaks from the Green Lantern Corps and goes rogue, using a yellow power ring created by the Qwardians. The Green Lantern film series was clearly headed that direction but never got a chance.
With the rebooted Green Lantern characters in the new DCEU, Sinestro could be introduced in the aforementioned Parallax possession storyline.
Perhaps multiple Green Lanterns could be possessed and when they are all saved, Sinestro decides that he no longer wants to play by the rules and goes rogue in the movies, as well. He could then set up his Sinestro Corps like in the comics, which would make for a very compelling threat in a future DCEU Green Lantern Corps film, which is nominally on the docket for some time in the near future.
One of the aspects of the DC Universe that has always set it apart from Marvel is its willingness to start things over from scratch. DC has had two major reboots since 1986, along with at least three minor reboots, depending on whether you consider "DC Rebirth" as major or minor (the other minor ones would be Zero Hour and Infinite Crisis). Meanwhile, Batman v Superman: Dawn of Justice already set up the idea that the timeline of the DCEU is not exactly set in stone.
Therefore, there appears to be a real opening in the film universe to play around with alternate realities and the Multiverse in general. Viewers of the Flash TV series are already familiar with the idea of Flash altering reality by going back in time and changing things, and since that alternate "Flashpoint" universe was literally the working name of the delayed upcoming Flash solo film, it seems like the DCEU is willing to work with alternate realities, as well. If that's true, it creates a great opportunity to work the Anti-Monitor into the film universe, since he is a villain whose whole set-up involves trying to interfere with the Multiverse, as well.
Something that has been a recurring theme in Geoff Johns' comic book work over the last two decades is the idea of taking comic book villains that were once considered relatively minor and upping their status so that they could stand on their own and even play major roles in company-wide crossovers, like Black Hand in Blackest Night. However, in the case of Eclipso, the "darkening" of the character actually took place even earlier in the work of Keith Giffen and Robert Loren Fleming.
Originally, Eclipso was just a villain who took over the body of a scientist, Bruce Gordon, during eclipses.
He then committed crimes before returning Bruce's body to him later on. Giffen and Fleming revealed that Eclipso is a much larger cosmic force than that and he introduced the concept of a giant black diamond that was blown up into a bunch of smaller diamonds. If a person were to hold one of those diamonds and become angry, they would be possessed by Eclipso. In Eclipso: The Darkness Within, Superman is possessed by Eclipso and the whole DC Universe has to team up to stop him. That is the perfect set-up for a future Justice League film.
Trigon is one of the most powerful villains in the DC Universe. He was born when a woman who was part of a mystical cult that worshiped the god Azar found herself in love with the dark deity. Their baby, Trigon, was born in Azarath, the dimension named after his father, where he quickly became a powerful being. He ruled over his first planet before he was even a toddler! He destroyed it when he was a little kid! By the time he became an adult, he was ruling over millions of planets in Azarath. However, Azarath was not enough for him. He wanted to conquer Earth, as well.
He seduced a member of a cult on Earth that was designed to destroy him and she gave birth to a daughter, Raven, who grew up in Azarath. Her people tried to teach her to control her emotions to keep herself from drawing Trigon to her. When she was a teenager, she traveled to Earth to warn the Justice League of Trigon's plan to invade Earth, but since she was half-demon, they turned her down. So she formed a new group of Teen Titans instead to help her. This would be a great way to introduce the Teen Titans into the DCEU, as they can be unrelated teen heroes, since Raven has no connection to the Justice League.
The Sun-Eater is such a threat that it opens up an entirely different take on a superhero film, sort of similar to that of Avengers: Infinity War, which is namely, "What do you do if you really cannot save the day?" The Sun-Eater was originally introduced in the Legion of Super-Heroes comic book stories set in the future. Created by the Controllers as a tool to destroy planets that they deemed too evil to live, the Sun-Eater would literally absorb the sun of a given solar system and the planets orbiting the sun would then slowly die off, as well, killing all of the denizens of those planets.
The Legion was so desperate to defeat the Sun-Eater that they actually released five of the deadliest villains in the galaxy to help them fight it.
They were no help and they actually escaped and formed their own super-villain team, the Fatal Five. The Legion finally succeeded in defeating it by one of their members, Ferro Lad, flying a bomb into the middle of the Sun-Eater and blowing it up. In modern times, though, that did not work, so the heroes of Earth had to deal with their sun being devoured. Superman lost his solar-based powers. Things were bleak. It would make for an interesting DCEU film to see the heroes have no chance of winning until, of course, someone makes the ultimate sacrifice. In the comics, Hal Jordan sacrificed himself to re-ignite the sun.
Perhaps a character who is based on bringing past characters back to life is not the type of villain that you would want to work into the DCEU just yet, but honestly, there have already been a number of notable deaths in the DCEU, so it might not be too soon to work Nekron into the mix. Nekron had been around for decades, but Geoff Johns turned him into a major threat during the Blackest Night crossover event, when Nekron created Black Lantern Rings that would re-animate dead superheroes and supervillains to give him an army of super-powered soldiers that literally could not be killed.
In the DCEU, there would be El Diablo, Slipknot, Incubus, Steppenwolf, Ares and Doomsday, who could be re-animated to be set against their former allies and foes. Not only that, but imagine if Steve Trevor, Jor-El and the Waynes were brought back to life, as well! Heck, Nekron might take control of Superman, also, due to his death in Batman v Superman: Dawn of Justice. The goal of Nekron is to destroy all life in the universe, so he is certainly a potent threat for the Justice League to deal with in the future.
Superman's old foe, Mongul, showed up in Metropolis one day scared out of his mind. He needed Superman's help against a powerful being known as Imperiex who had destroyed Mongul's planetoid attack base known as Warworld. If Warworld could be destroyed, then surely Earth was in trouble, as well, so Superman teamed up with Mongul and they defeated Imperiex after a long and brutal battle. In the wake of their victory, they discovered a shocking fact -- the "Imperiex" that they had just defeated was actually only a probe sent by the real Imperiex.
The real Imperiex was much bigger and much more powerful.
Imperiex, you see, was obsessed with the universe containing a "flaw" that needed to be eliminated. The way to do so was to create a second big bang. The only way that this could be achieved would be to "hollow" out the universe. That would involve destroying Earth, since the planet turned out to be center of the DC Multiverse. Since the universe itself was at risk, Earth was forced to team up with Apokolips, since Darkseid wants to rule over the universe, not destroy it. So Imperiex would be a fascinating foe for a future DCEU film where Darkseid is suddenly an ally of the heroes.
Krona is oddly heavily involved in a number of major events in the history of the DC Universe. He was a scientist on Oa millennia ago who was obsessed with the beginning of the universe, even though he was routinely warned that traveling to the start of the universe would result in him going mad. He couldn't stop himself, though, and traveled to the beginning, accidentally altering the creation of the universe so that the Multiverse was born, as well. The Multiverse being born also led to the Anti-Matter Universe being born, so he is responsible for both the Monitor and the Anti-Monitor.
His actions were so drastic that his fellow Oans felt they had to make sure that something like what he did could never happen again, so they decided to become the Guardians of the Universe. They made Krona into a being of pure energy as a punishment, but he has become corporeal many times in the years since and he is naturally quite mad from the experiences that he went through. Thus, he always has some sort of evil plan up his sleeve. Being such a powerful being with connections to so many different parts of the DC Universe, he would be a worthy foe in the DCEU.
10 WHITE MARTIANS
Longtime fans of Superman realize that the prisoners of Krypton were sent into the Phantom Zone as punishment. This worked out in a kind of a strange way because Krypton was then destroyed and some of the only survivors were the very worst scum of Krypton. The Phantom Zone is a bad place to be, as well, of course, but eventually they always seem to escape from their prison. That is the same thing that happened to the White Martians, the evil warlike cousins of the Green Martians of Mars. The White Martians were exiled to another dimension, just in time for the Green Martians to all be wiped out, with only J'onn J'onnz, the Martian Manhunter, left to survive the death of his people.
The White Martians were used beautifully in Grant Morrison's JLA, where they used their shape-shifting ability to trick the people of Earth into thinking that they were a brand-new superhero team here to help the world, but secretly they were taking it over. This plot could be used pretty much completely in the DCEU and the story could also be a way of introducing the Martian Manhunter into the DCEU, as he could help the League take down his fellow Martians.
Like the Sun-Eater, the villainous Mordru began his comic book career as a foe of the Legion of Super-Heroes in the future. Later writers then adapted the character to make him a foe of the modern day heroes, as he was established in the Legion stories as basically being immortal, so he could easily be alive in modern times (typically without the grey beard he has in the distant future).
As one of the most powerful magicians in the DC Universe, Mordru would be an excellent foe for the Justice League.
Powerful magic-wielders are some of the only people in the DC Universe who Superman has trouble fighting against, after all. So he would be a lot stronger of a threat than, say, Steppnenwolf, who seemed doomed as soon as Superman showed up on the scene. Not only that, but since he originated as a Legion foe, this could be an interesting way to introduce the Legion of Super-Heroes into the DCEU. Simply have the beginning of the movie be Mordru facing off against the Legion in the future. Have it last a couple of minutes and introduce a few of the Legionnaires, and then have Mordru escape to the present day, which is where the rest of the movie starts.
The very first foe that the Justice League faced off against in their ongoing comic book title was Despero. He was introduced as a world conqueror who ruled over the worlds he won like a tyrant. He had telepathic powers due to the third eye that he grew when his race was mutated by a form of nuclear energy. In the original comics, Despero was a crafty foe, who often relied on his telepathy more than brute strength.
Over the years, he exposed himself to the nuclear energy that formed his people (known as the "Flame of Py'tar") to mutate himself further into a hulking mass of muscle, making him a major physical threat as he could pair his powerful muscles with his telepathic powers. He landed in Gotham City and began to remake the city in his image before the Justice League were barely able to stop him. He has always viewed the Martian Manhunter as his greatest foe, as they are both aliens who interact with the Justice League, but J'onn works with the League while Despero always tries to destroy them. It would be interesting to see him introduced in the DCEU and then see him return for the final fight in the film in his mutated form.
The literal first supervillain that the Justice League ever faced in the comics was Starro the Conqueror, who debuted in Brave and the Bold #28, the same comic book that introduced the Justice League of America. When he originally appeared, he was able to brainwash a small town and empower other starfish to do his dirty deeds for him, including almost nuking the entire planet! However, the Justice League was able to stop him with the help of a local teenager named Snapper Carr, who realized that quicklime was able to cancel out Starro's powers. Snapper lived in the town that had been enslaved but was immune since he had just been working with quicklime.
Starro evolved into a new form, which is probably his most famous look.
He spawned millions of little starfish that he would eject over a planet and attach themselves to people, covering their faces and forcing them to obey him. It is a brilliant visual design to see millions of people covered with starfish on their faces all talking as one. This is how Starro conquers planets nowadays. That would translate beautifully into the DCEU, as the members of the Justice League could fall, one by one, until there are only a handful of heroes who have not been controlled. This could lead to an awesome sequence where, say, a Starro-controlled Superman has to face a still-free Wonder Woman... or vice versa!
Originally basing the character on Nebula Man, who was introduced by Len Wein and Dick Dillin for the 100th issue of Justice League of America, Grant Morrison dramatically re-made Neh-Buh-Loh as part of his "Seven Soldiers of Victory" series of books. He set the story up in the pages of JLA Classified, where the Justice League and the Ultramarines enter a new universe called Qwewq in pursuit of the villainous Black Death. The Black Death ended up poisoning this new universe and it eventually turned into Neh-Buh-Loh. He possessed one of the Ultramarines to gain a corporeal form.
Neh-Buh-Loh then traveled through time and was part of a number of stories involving the character who would form the basis of Morrison's Seven Soldiers team, including Shining Knight, who Neh-Buh-Loh met in the distant past. As a living universe, Neh-Buh-Loh had an amazingly cool-looking visual and his time-spanning set-up would translate really well to film, as he could be shown fighting against different heroes at different points in time before he takes on the Justice League in the present day. His visual, though, would require some advanced computer graphics to make it look good, so that might be a bit too much for the current DCEU to handle.
Justice League of America was on a bit of a hot streak with notable new villains in 1971-72. A few issues before the Nebula Man made his bow, Mike Friedrich and Dick Dillin introduced Starbreaker. Starbreaker appeared as a normal humanoid, but it turns out that he was a sort of planetary level energy vampire. In other words, he could devour the energy of a whole planet of people, draining it just like a vampire would drain a person of blood.
Later on, we discovered that Starbreaker is actually the adult form of a Sun-Eater.
Starbreaker first tried to destroy Rann, the home of the space explorer, Adam Strange. The Justice League helped stop him there, but he then set his sights on Earth. The League stopped him eventually and he was held captive by the Guardians of the Universe before eventually breaking free and taking on other planets in the DC Universe. His next target was Almerac, home of Maxima. Later on, we discovered that Starbreaker is actually the adult form of a Sun-Eater. His people apparently are born as Sun-Eaters and grow up into energy vampires. A fun use of Starbreaker in the DCEU would be to introduce other planets and aliens. For example, the Justice League could help stop him on Planet A, which could introduce that planet and its people to the DCEU.
Introduced in the 1991 DC Comics Annuals summer crossover event, Armageddon 2001, Monarch was a tyrant who ruled over Earth in the distant year of 2001 (naturally, that part would need to be changed). A being from the future traveled back to 1991 to reveal a shocking truth -- Monarch in the future was actually a superhero back in 1991! The being, known as Waverider, would go around and test various heroes to see what their future would look like and see if they became Monarch.
It turned out that Hawk, of Hawk and Dove, was the hero who would turn evil. In actuality, Captain Atom was meant to be the guy, but that twist leaked ahead of time, so DC Comics abruptly changed the comic to make it Hawk instead. In the DCEU, it would obviously have to be someone else, but an interesting concept would be to play with the idea of a changeable future. For instance, the Snyder films hinted that Superman would go evil, so wouldn't it be interesting if Superman was revealed to be Monarch, but then the heroes were able to change the future and keep Superman from breaking bad? That could make for a powerful film.
Introduced as part of the crossover event, Underworld Unleashed, Neron is an attempt to give the DC Universe a devil character of their own, like how Marvel has Mephisto. Underworld Unleashed involved Neron offering Faustian bargains to the various supervillains of the DC Universe. He would upgrade their powers in exchange for their souls. The whole thing was really just about revamping DC's supervillains.
However, that basic setup would actually translate really well to the DCEU. For instance, you don't have to be familiar with all of the supervillains who are being transformed to simply establish that there is a demon who has come to Earth and is upgrading the supervillains of the DCEU to make them bigger threats. That would actually work really well as a film set-up, as the upgraded villains could take on the Justice League, while a few members of the League would be forced to try to deal with Neron directly. This could be a way to introduce Zatanna into the DCEU, or perhaps even work John Constantine into the picture, to set up a future Justice League Dark movie. Neron could also work well as a background villain, sort of like how Mephisto worked in Infinity Gauntlet.
It is a bit unclear precisely what rights that DC has to Jim Lee's Wildstorm characters when it comes to multimedia adaptations. However, for the sake of this list, let us assume that all of the Wildstorm characters are available to be used in the DCEU. If that is the case, then it could be very interesting to work the basic set-up of the original WildC.A.T.s comic book series into the DCEU. You see, the idea behind that series is that two alien races, the Kherubim and the Daemonites, have been in the middle of a war for millennia. A long time ago, a group of Kherubim and Daemonites crash-landed on Earth.
The human-looking Kherubims integrated into Earth society, while the Daemonites got by by possessing human bodies.
Their ultimate goal was to take over Earth entirely so that they could it in their war with the Kherubims. Helspont was a Daemonite military leader who got a hold of a powerful alien host body, making him look different than the other Daemonites but also giving him a lot more powers. The idea of the Daemonites living among the humans and working against them would serve well for the backdrop for a film.
Warner Bros. appears ready to bring the New Gods to the silver screen with star director Ava DuVernay being behind the planned film. It is unclear whether this film will integrate the New Gods into the DCEU or not. If they are only slightly integrated into the DCEU, then an interesting way to further that connection would be the use of the villainous Mageddon. Introduced in Grant Morrison's JLA run, Mageddon was a sentient machine that destroyed the Old Gods that predated the current Fourth World. It was kept prisoner for millennia but it then escaped and set its sights on Earth.
It had these spores that it released that drove the people of Earth mad with rage and fear, making the planet easier for Mageddon to destroy with its anti-sun powered weapons. It even managed to break Superman's mind and make him into its servant, with the Man of Steel dragging the ancient cogs that powered Mageddon so that it could move. Mageddon is so massive that it makes the Earth look like a golf ball in comparison. It would be just the kind of awe-inspiring foe that would make for a devastating addition to the DCEU, especially as a connective tissue between the New Gods and the Justice League.