"Crisis on Earth-X": Where Is Earth-1's Supergirl?

Supergirl is set to return to television screens this week, with fans hoping that their burning questions will soon be answered. But before the back half of the season officially begins, we thought we'd examine one lingering question from The CW's "Crisis on Earth-X" crossover.

In the crossover's first installment, the heroes were met with an attack from Earth-X invaders, causing them to try to uncover more information about the evil Earth. Along the way, Harry Wells (Tom Cavanagh) provided a very basic understanding of the multiverse, and revealed that each "Earth" has its own version of Kara Danvers/Supergirl (Melissa Benoist).

This confirmed an age-old theory about how the Arrowverse operates: that there is, in fact, a Kara that exists on Earth-1. The Earth-1 shows -- The Flash, Legends of Tomorrow, and Arrow -- haven't really toyed with that possibility a lot aside from acknowledging that Supergirl isn't a publicly known superhero on Earth-1.

With that in mind, where exactly could Earth-1 Kara be? What reason could be behind the fact that she hasn't really been introduced in the Arrowverse yet? Here are a few possibilities.

Power Girl

Of course, this is the most glaring theory, as it has been suggested by fans almost since Supergirl's inception. Kara's Earth-2 comic counterpart has been a fan-favorite for years, and the topic of whether or not she could enter the Arrowverse through Earth-1 or otherwise has been debated about for quite a while.

"There's still an endless treasure trove of DC Comics characters, and stories, and titles that we haven't even come close to touching yet," former showrunner Andrew Kriesberg said back in 2016. "We're certainly not wanting for ideas for the future. We know that they're out there for us."

Having Power Girl be Earth-1's version of Kara could work, although it would require some sort of reworking of her origins. After all, Power Girl takes on her moniker and occasionally controversial costume as a way to differentiate from her Earth-1 self. But within the confines of Earth-1 -- especially since Superman isn't established on that Earth either -- Kara could easily just take on the Power Girl mantle on her own.

No Superman, No Supergirl

This is kind of a related theory, which creates an almost infinite number of possibilities in terms of Earth-1 Kara's origins.

As Supergirl established minutes into its pilot episode and throughout its pre-episode intro, Superman was the one who found Kara when her pod landed on Earth. Superman then brought Kara to live with the Danvers family, setting her on the path we've already seen unfold.

But what if that didn't happen? After all, Superman isn't a public figure on Earth-1 to our knowledge, which means that either Earth-1's Clark Kent is still a mild-mannered reporter, or he didn't even get to Earth to begin with.

Maybe something along the lines of JLA: The Nail happened, preventing the Kents from ever finding Clark's pod to begin with. In a way, that would have a chain reaction on how Supergirl got to Earth, and who exactly found her when she got there.

Kara's Pod Landed Somewhere Else

Which brings us to this possibility, which has a couple different roots within the world of comics.

Even if Clark exists on Earth-1, there's a chance that he never was able to find Kara's pod, because it landed somewhere completely out of his control.

This could manifest in a couple different ways depending on how the Arrowverse's writers wanted to handle it. Kara could be raised by the Amish, a la Superman's storyline in the aforementioned JLA: The Nail, or she could've been brought up to be a Navy super-soldier as seen in the early days of the Trinity series. Her pod could also still be in cryosleep at the bottom of some body of water, similar to her character's Smallville origins.

Or, who knows? Maybe her pod is still stuck in the Phantom Zone.

Stuck in ARGUS

Another possibility, regardless of where Kara's pod actually ended up, is that she's currently being hidden in one way or another. The possible culprit? ARGUS.

The government agency was first introduced in the early days of Arrow, and has connected to all three of the Earth-1 shows in one way or another. As fans have seen, ARGUS can occasionally get up to some shady things, whether keeping supervillains locked up as guard dogs or installing an anti-metahuman police state in the future.

Someone with a skillset as powerful as Kara's would certainly get on ARGUS' radar, potentially before the rest of the world realized it. This could mean that Earth-1 Kara is just hidden in some sort of ARGUS prison, providing a perfect opportunity for the Arrowverse's heroes to get her out.

With Earth-1's Legion

At this moment, fans have only seen the tip of the iceberg in terms of Supergirl's version of the Legion of Super-Heroes. But considering what we know about the group in the comics, there's a very good chance that Kara could play a different role in their Earth-1 creation.

In the comics, the Legion is rooted in their adoration for Superboy, leading to them plucking him out of his time period to recruit him for the group. A similar thing has sort of been seen within Supergirl, as Mon-El (Chris Wood) accidentally time-traveled to the 31st century, and helped form the group in Kara's memory.

There's a chance that Earth-1's Kara could have accidentally time-traveled to the Legion, and became a long-standing member of the group. It would explain why those on Earth-1 haven't heard of her yet, and would create a pretty epic way for her to return. (Plus, you know, it would also help another "Crisis on Earth-X" fan theory.)

Time Travel

Now, this one feels a little out of the box, but it almost falls into the "so crazy it just might work" category.

As Legends of Tomorrow has shown, the Arrowverse timeline can be a sensitive thing, with characters and historic figures bouncing in and out of certain eras. With that in mind, it would be pretty neat to discover that Earth-1's Supergirl is actually an anachronism, or that her existence was prevented by one in some way.

Not only would it give the Legends a pretty unique quest, but it would give Benoist a completely new -- and potentially hilarious depending on what time period she was sent to -- avenue to play Kara.

Supergirl returns on Monday, January 15th, at 8/7c on The CW.