Welcome back to The Hollywood Reporter's weekly DC TV Watch, a rundown of all things DC Comics on the small screen. Every Saturday, we round up the major twists, epic fights, new mysteries and anything else that goes down on The CW's Arrow, The Flash, Legends of Tomorrow, Supergirl and Black Lightning and Fox's Gotham. Note: Supergirl, Arrow and The Flash aired the three-part "Elseworlds" crossover this week, Legends of Tomorrow and Black Lightning aired fall finales and Gotham did not air a new episode this week.

The Flash, Supergirl and Arrow's "Elseworlds" crossover

The big news: While so much happened in this year's Arrow-verse crossover, it was the final end tag that blew the entire universe wide open. The theme of next year's crossover has been revealed to be "Crisis on Infinite Earths," the comic book arc that all the Arrow-verse shows has been building toward for the past five years.

What it means: Even for the casual viewer who has not read many comics, the clues that the Arrow-verse was heading in this direction were planted from the beginning. When The Flash first debuted, Barry Allen (Grant Gustin) had access to a future newspaper headline: "Flash Missing, Vanishes In Crisis," which has always meant the show was going to take on "Crisis" (for reasons explained below). It was also referenced throughout this entire crossover: The Monitor (LaMonica Garrett) kept saying that a "crisis" was imminent, and he was rewriting reality to test every Earth to see if there were any heroes good enough to face whatever was coming. But the end tag confirmed that he was indeed trying to prepare Earth-1 (along with all the other alternate versions of Earth) for "Crisis on Infinite Earths."

So what happens in "Crisis" and why is it such a huge deal? The huge, 12-issue series published in 1985-86 is regarded as one of the most important comic arcs of all time and was designed to get rid of the multiverse and make one continuity for readers. The effects were far-reaching. The evil being The Monitor warned was coming was his evil counterpart, The Anti-Monitor, who began destroying Earths with antimatter so he could become the ruler of all realities.

This means Garrett will most likely return next year to reprise his role as The Monitor while also pulling double-duty to play the evil twin. The Monitor does return briefly to recruit heroes from all Earths to stop The Anti-Monitor, but he's killed pretty quickly. The Anti-Monitor, however, plays a much bigger role. Another face that could (and probably will) return next year for the crossover is Psycho-Pirate (Bob Frazer), aka that crazy dude with the gold mask seen at Arkham Asylum in this week's "Elseworlds" crossover. He becomes The Anti-Monitor's right-hand man and was yet another clue that "Crisis" was coming before the end tag confirmed it.

But what does this mean for the Arrow-verse heroes fans know and love? Prepare for deaths. Major, major deaths. The biggest consequence from bringing "Crisis On Infinite Earths" to life on the small screen is that two main heroes, Supergirl (Melissa Benoist) and The Flash, are under the microscope. Supergirl is the first major casualty in the comic arc, and The Flash dies shortly thereafter in the heroes' attempts to stop The Anti-Monitor, bringing that future headline to fruition.

But will The CW kill off two of the network's biggest characters? Doubtful, honestly, considering The Flash is its top-rated series and Supergirl has done wonders for the network's newly launched Sunday lineup. But in order to bring the full scope of "Crisis" to life, the network absolutely should not pull any punches. Kill off heroes! Change the game! Otherwise, why even attempt to do "Crisis?" If The CW does follow the comic arc to the point of killing off Kara and Barry, what does that mean for Supergirl and The Flash as shows if their titular characters die? "Crisis" has the potential to either be the biggest moment for the entire history of the Arrow-verse, or potentially the biggest letdown since The Flash only followed "Flashpoint" for one episode (instead of the entire season as was expected).

Who else could die? If Barry and Kara aren't killed off (which they probably won't be as the network's most bankable characters/stars/shows), the next likely candidate is Oliver Queen (Stephen Amell). The Green Arrow is the hero that started The CW's DC Comics multiverse so he may play the biggest role in next year's potential multiverse-ending crossover. This year's crossover saw him make a mysterious deal with The Monitor to save both Barry and Kara's lives (they were supposed to die in their attempt to slow time to stop this year's crossover villain). He probably traded his life for theirs, knowing they were "good" enough to stop whatever was coming whereas he was just filled with anger and revenge. Plus, Arrow has gone on for seven seasons, and could shuffle off into that good night with a successful, long run under its belt should its star character die in a blaze of glory in the crossover. But it also is the only show that could, at this point, successfully continue on without its star, as it has introduced an entirely new generation of heroes in the future-set storyline and even a new Green Arrow with Oliver's half-sister Emiko Queen (Sea Shimooka) in the present.

But one life doesn't balance out two lives, so another hero is also most likely going to die. Supergirl sacrifices her life to save Superman's in the comics, so the inverse could come true onscreen. Superman (Tyler Hoechlin) is the obvious choice for the second major casualty, both because he wouldn't take down an entire show with him and because he would serve as an equal trade for Supergirl, laying down his life to save hers. It would be all the more heartbreaking to lose him, however, as he just received news from Lois Lane (Bitsie Tulloch) that she's pregnant with his child. So if Superman were to die in the fight against the Anti-Monitor, he would do so knowing that his legacy (and love) would survive with Lois and his child, and the world would be in good hands with Kara. He did leave Earth-38 at the end of this year's crossover to live with Lois on Argo City and their unborn child, and he told Kara point-blank he felt he could leave because Kara was the hero the world needed. If that doesn't sound like the groundwork for Superman's death has been set, you haven't been paying close enough attention.

What else could happen in 2019? One of the coolest moments that could (and should) happen during the "Crisis" crossover is the mic-drop moment when all the heroes and villains stop fighting each other and come together, united by the iconic entity The Spectre, to try and stop The Anti-Monitor from traveling back in time to prevent the creation of the multiverse (since that would mean the end of everything as everyone knows it). It's an incredible moment with far-reaching implications to see all the iconic heroes and villains setting aside their history of grudges and hatred, working towards one common goal. Just imagine seeing all the Arrow-verse heroes and villains from years past working together and all the amazing moments and one-liners that would bring.

How the Arrow-verse could change: In addition to the two major hero deaths, "Crisis" could change the makeup of the Arrow-verse forever. At the end of the comic arc, the heroes (and villains) prevail using time travel, defeating The Anti-Monitor in the past but not before all the Earths merge into a single shared universe, meaning that the multiverse was a thing of the past. All the heroes and villains now lived in the same universe. When everyone returns to the present, only a few remember the original realities (although none are characters in the Arrow-verse) and are sent a pocket "paradise" dimension. Everyone else is left in the new reality, and all of DC Comics' series were rebooted into the "Post-Crisis" era. Wally West (Keiynan Lonsdale) even replaced Barry Allen as The Flash. Black Lightning would finally be able to crossover with the Arrow-verse. Supergirl could come visit the other shows without having to use a multi-dimensional breaching device. The possibilities are literally endless.

And remember that when "Crisis" got rid of the multiverse, that meant countless versions of Earth were destroyed before the remaining five were combined into one new Earth. That means a ton of other heroes and villains could (and should) die when the Arrow-verse brings "Crisis" to life next year. Again, the possibilities are literally endless considering how many heroes and villains have been featured on the Arrow-verse so far, and how many more have yet to make their live-action debut.

Of course, the effects didn't last forever. "Crisis on Infinite Earths" actually became part of a larger trilogy, and the second part, "Infinite Crisis," restored the multiverse 20 years later. But that's two decades later, so prepare for the effects, whatever they may be, of "Crisis" to be pretty permanent in the Arrow-verse for the foreseeable future.

For more on the rest of the crossover, including Batwoman's (Ruby Rose) debut, check out The Hollywood Reporter's coverage here.

Legends of Tomorrow

The big news: In the reality-breaking midseason finale, Constantine (Matt Ryan) was forced to once again doom his love Desmond (Christian Keyes) to Hell to set the timeline right. But the demon he banished with Desmond seems to have made his way back to Earth in Desmond's body and is working with Nate's (Nick Zano) father Hank (Tom Wilson) on the mysterious and probably evil Project Hades.

What it means: Nothing good ... and fans will have to wait quite a while to find out what happens next, as new episodes will not return until April. It does probably signify that Hank doesn't know what he's doing is wrong and is being manipulated by a literal demon from Hell, so any father-son ire resulting from the inevitable discovery of Project Hades will be short-lived and not permanent. Also, the reality-bending adventure finally helped Charlie (Maisie Richardson-Sellers) realize she plays an important part of the Legends team. The power of friendship!

Other noteworthy moments: In the show's most meta moment yet, when the Wavedrider's AI Gideon told the team they missed calls from "Barry, Oliver and Kara," Ray (Brandon Routh) replied, "Sounds like the annual crossover!" Nate's "That's going to be a hard pass" was perfect.

Black Lightning

The big news: When Black Lightning returns in January, Jennifer (China Anne McClain) will finally suit up as Lightning. Check out the first look at her superhero suit, below.

What it means: While the midseason finale ended with Jennifer still on the run with Khalil (Jordan Calloway), this reveal means she will eventually reunite with her family in a pretty big way. Not only will she forgive them for trying to limit her usage of her powers and keeping her from Khalil, but she will also join up with her father and sister on Team Black Lightning.

Other noteworthy moments: A new meta-human threat is making its way to town, as the end tag revealed a powerful assassin with teleporting abilities just received a new assignment in Freeland. Was he hired by Gambi (James Remar), or is he coming for Team Black Lightning?

Looking Ahead

While most of The CW's DC shows won't return until the middle to end of January, Fox's Gotham will be the first series to debut in the new year. The final season premieres Jan. 3 and will bring the total episode count of the series to 100. But don't fret: The Hollywood Reporter's DC TV Watch will be bringing you new scoop and analysis throughout the entire winter hiatus, so keep checking back here every Saturday morning.

Supergirl returns Jan. 20, Arrow and Black Lightning return Jan. 21, The Flash returns Jan. 15 and Legends of Tomorrow returns in April, all on The CW; Gotham returns Jan. 3 on Fox.