The highly anticipated Arrowverse crossover "Elseworlds" technically doesn't launch until Sunday, Dec. 9, with a special episode of The Flash. But fans have been counting down the days until The Flash, Green Arrow and Supergirl share the screen with Superman and Batwoman, which is why few expected to see the opening volley of the reality-altering event last night.

In the closing moments of this week's episode of Supergirl, viewers were transported in a post-credits scene to Earth-90, home of John Wesley Shipp's 1990 series The Flash. There, a veritable league of superheroes lay dead on a battlefield, defeated by the Monitor, with only Shipp's speedster left standing. There were some recognizable costumes among the carnage, and perhaps even a few surprises throw in. So who were all of the DC characters who fell to this new threat?

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Stargirl

Elseworlds-Stargirl

The first glimpsed casualty of the Earth-90 massacre is one recognizable to fans of DC's Legends of Tomorrow: Stargirl. Courtney Whitmore's alter ego can be seen lying dead in the costume she wore on that series. Of course, given that this is Earth-90, this is undoubtedly a different Stargirl than the one from Legends -- particularly considering that Legends of Tomorrow's Stargirl was already killed during the second season.

Huntress

Elseworlds - Huntress

As the camera pans from Stargirl, another familiar female crime-fighter comes into view. It's difficult to say with 100-percent certainty, but it certainly looks like the Huntress. The domino mask and leather coat lead us to believe that this is the Earth-90 version of Oliver Queen's former flame, who briefly appeared in seasons 1 and 2 of Arrow.

Firestorm and ... Spartan?

Arrowverse-Firestorm

Another superhero who fell at the hands of the Monitor is one of the most powerful in the Arrowverse: Jefferson Jackson's Firestorm. Given that the Jefferson we know from Legends of Tomorrow is no longer Firestorm, this is more likely the Earth-90 version of the nuclear-powered hero.

But there's another fallen superhero in the same shot, at the lower left. It's difficult to say who that character is, but it could be either the Guardian or, more likely, Spartan. Both wear protective helmets, but the dark uniform leads us to believe it may be another version of John Diggle's alter ego. However, given that this is another Earth, it could always be a hybrid of the two superheroes. Perhaps, on Earth-90, John Diggle is known the Guardian.

Earth-90 Captain Cold

Supergirl stringer Earth-90 Captain Cold

The next casualty of Earth-90 is someone we didn't necessarily expect to see fighting alongside superheroes. While we have seen Wentworth Miller's Captain Cold in the Arrowverse, there was another version of the frigid villain in the 1990s The Flash series. The alter ego of Leonard Wynters, this Captain Cold was played by actor Michael Champion and sported white hair, just like the deceased character seen here.

That leads us to believe the cataclysmic attack by the Monitor on Earth-90 was enough to have foes become allies in the face of adversity. Sadly, only the Scarlet Speedster got to walk away from this fight.

NEXT PAGE: A Smallville Character May Be Among Earth-90's Fallen

Jesse Quick

Elseworlds - Jesse Quick

John Wesley Shipp's Flash may have been the sole star of his series, but he may not be the only speedster on Earth-90. After all, Earth-1, home of Barry Allen's Fastest Man Alive, is rife with other speedsters. It, therefore, only makes sense that there would be others on Earth-90 as well.

This looks an awful lot like Jesse Quick, who has appeared on The Flash for multiple episodes. While the version of the character we know hails from Earth-2, it seems like the Jesse Quick from Earth-90 was taken out.

The Ray

Elseworlds - The Ray

The Monitor's next victim can only be identified by his helmed. While his body is nowhere to be seen, it sure looks as if The Ray fell in battle. The costumed identity of Ray Terrill, The Ray was introduced in last year's Arrowverse crossover, "Crisis on Earth-X," as played by Russell Tovey.

Of course, there is no way for us to know which version of the character perished on Earth-90. After all, the Earth-X Ray traveled to alternate dimensions, which means there's a chance this could be the version of the superhero we already know -- especially considering the identity of another Earth-90 victim.

A Few Legends

Elseworlds - Legends

Three characters that became closely associated with the Legends of Tomorrow are seen dead on the Earth-90 battleground: Hawkman, Hawkgirl and, most notably, Captain Cold -- only this time, it appears to be a familiar version of the latter. After all, he's wearing the parka we've seen Wentworth Miller sport on The Flash and Legends of Tomorrow.

However, given that Earth-90 already has a Captain Cold in Leonard Wynters, the presence of a second one is noteworthy. It's possible that this Earth actually had two versions of the Flash rogue, but it's also possible this is the Leonard Snart from Earth-X, who was in a relationship with The Ray, another casualty of this battle. Hopefully, Shipp's Flash will offer more information in the actual crossover that will sort out which versions of the characters died.

Green Arrow

Elseworlds - Smallville Green Arrow

The final hero that appears defeated is one that's sure to get a lot of fans talking: Yes, this is Green Arrow, but not Stephen Amell's version. Instead, this appears to be the costume worn by actor Justin Hartley on the fan-favorite Smallville.

Of course, Smallville and the '90s Flash don't share the same Earth, but it's possible there are elements that cross from one Earth to the next. Oliver Queen may not look like Stephen Amell on every Earth -- just like Barry Allen can look like both Grant Gustin and John Wesley Shipp. Either way, this is a costume fans never thought they would see on the screen again, so it's definitely a nice touch.

RELATED: Elseworlds Crossover Episode Synopses Released By The CW

This year's Arrowverse crossover event will involve the casts of Supergirl, Arrow and The Flash. The event will unfold over three nights, starting with a special episode of The Flash on Sunday Dec. 9, at 8 p.m. ET/PT. Then, it continues Monday, Dec. 10, with Arrow, and concludes on Tuesday, Dec. 11, with Supergirl.