Things had gotten a little complicated for DC Comics circa 1986. The bulk of the company's modern heroes occupied Earth-1, but there were others: the WWII-era Justice Society hung out on Earth-2. Captain Marvel/Shazam and the Marvel Family (a 1970s DC acquisition) had adventures on Earth-S. The powers that be came to see the multiverse as a barrier to entry--confusing for new readers in a way that was pushing them into Marvel's much simpler single, unified universe. So there came a Crisis.
That word had a very specific meaning at DC: 1963's "Crisis on Earth-One!" in Justice League of America #22 had kicked off an annual tradition of crossovers between the JLA and the WWII-era Justice Society of Earth-2. So Marv Wolfman, George Pérez, and their all-star team of collaborators pitched an ultimate crisis--one that would bring the various DC universes together in-story, and serve as a significant reboot for the entire line. Though still controversial, they weren't messing around: the twelve-issue main series (supported by dozens of crossover issues) saw a huge death toll and made a firm break with the past as the Anti-Monitor swept through the multiverse, destroying worlds along the way.
Many heroes got updated origins; Superman, Batman, and Wonder Woman in particular inspired some all-time great work from their new creative teams. There were also unintended consequences, naturally, and DC spend the following twenty years or so doing small reboots of its big reboot in order to iron out the complications created by that effort to simplify things. Though some fans loved it, and some hated it, there's no denying that it did what other mega-events only promise: it changed things forever, with DC's history still marked by fans as "pre-Crisis" and "post-Crisis." We'll see if the long-teased TV version will be able to say the same.
With the Crisis fully underway, here's a handy guide to the many, many references and easter eggs that showed up in the Supergirl episode that kicks everything off.
The episode begins with flashes of several other Earths—each strangely familiar. The man reading the newspaper at the outset is Gotham Globe reporter Alexander Knox, whom you’ll recall from Tim Burton’s 1989 Batman movie (thus: Earth-89). Then it’s off to Earth-9, which we learn is the home of the Titans from the DC Universe streaming service's series via appearances by Jason Todd and Hank Hall (the latter played by Alan Ritchson, formerly Smallville's Aquaman). Earth-X is home to Russell Tovey’s The Ray—last seen live in the “Crisis on Earth- X” crossover from a couple of years ago. In that world, the Nazis won World War II and the Freedom Fighters battle for...we’ll, freedom. Quality Comics was the company that owned those characters it was bought by DC, which is how they wound up on a different earth.
"Holy crimson skies of death!"
Finally: the unmistakable Burt Ward, Robin in the 60s-era Batman series, walks down a Gotham street on Earth-66.
Though it’s undeniably cool to see these old friends, it’s entirely possible that we’re seeing them all wiped from existence.
The Arrow-verse has played a very long game with this character—so much so that it would have been easy to assume that the name “Lyla Michaels” had been plucked at random from DC’s long history. Introduced way back in Arrow season one and played by Audrey Marie Anderson, Lyla was an A.R.G.U.S. agent and ex-wife of Oliver’s best friend and co-vigilante John Diggle. Over the following seasons, she joins the show’s version of the Suicide Squad before remarrying Diggle, giving birth to their daughter Sara (who, due to some Flash-related time-travel shenanigans ultimately becomes their son John Jr.), and becoming the director of A.R.G.U.S. following the death of Amanda Waller.
Again: none of this seems like it would have anything to do with the comics character who’d been raised by the Monitor to be his assistant. The relatively grounded first season of Arrow seems miles removed from the inter-dimensional, multi-series crossover going on now—was it planned from the beginning that the TV character’s arc would dovetail with that of the comic book version? It’s hard to imagine. But maybe?
On the page, Harbinger created several copies of herself in order to more efficiently travel the multiverse recruiting heroes. One of the doppelgängers is corrupted along the way, and spreads that corruption to the rest of her sisters, leaving her an agent of the Anti-Monitor.
First appearing in 2015 and created by legendary Superman writer/artist Dan Jurgens, Jonathan Samuel Kent is, just as in the show, the son of Clark Kent and Lois Lane. Even though he was born just four years ago, he’s already aged into the role of Superboy. Having had several adventures with his best friend Damian Wayne, son of Batman, he’s currently living 1,000 years in the future with the Legion of Super-Heroes.
Lois and Clark are living on ill-fated Argo, the home of Supergirl that managed to survive the destruction of Krypton. Kara’s mother Alura is played by Erica Durance, Smallville’s Lois Lane.
Kell Mossa, on the page, was one of the greatest scientists of his Earth. But he dug too far, and too deep, into the secrets of the multiverse. His attempts to view the origins of everything drew the attention of the Anti-Monitor (who's only been teased in the TV series--so far), drawing his attention and giving him access to the antimatter present at the beginning of time. Saved by the Monitor from the destruction of his universe, he's now forced to travel the multiverse witnessing the Anti-Monitor's reign of destruction by way of penance. The Arrowverse version is Nash Wells, played by series regular Tom Cavanaugh as the latest incarnation of the Harrison Wells character who shows up each season.
The comic series had a pretty high body count, and the TV version looks like it might also. There may be a difference though: the death of Oliver Queen has been teased for months now, but he wasn't one of the casualties of the book. The two most impactful heroic deaths there were, however, characters we also know from the show: the Barry Allen Flash, and Supergirl. In the comics, Barry was soon replaced by his former protege Wally West (Barry got better, but it took about 20 years), while Supergirl was written out of existence for a time. Crisis lead to a Superman reboot that imagined him as the lone survivor of Krypton, paring away the various other survivors who had popped up over the decades. A new Supergirl did eventually show up--an alien shapeshifting goo, who became a teenage rebel, then an angel (all one character, none from Krypton--and cooler than she might sound). The original Kara, too, got better after a while.
Come back for part two: the references and easter eggs featured in Batwoman.