The CW had a major hit with last week's DC TV crossover that brought Kara Danvers to Earth-1 to help Oliver Queen, Barry Allen, and the time-traveling Legends battle the invading Dominators. Supergirl went back to Earth-38 at the end of the crossover, leaving us to once again wonder whether we might see another version of the character from a different Earth. There's definitely a precedent for two different superheroes named Kara Zor-El in DC Comics, and Supergirl executive producer Andrew Kreisberg had this to say about the possibility of a second Kara in the aftermath of the crossover:
We hadn't discussed [introducing Power Girl] formally, but I think that certainly after these three episodes, there's literally no limit to the things we can do.
Supergirl hasn't really dealt with doppelgangers from different Earths just yet. Earth-38 is so different from Earth-1 that heroes like Green Arrow and the Flash don't even exist, and Earth-1 obviously doesn't have a Supergirl or Superman or even Batman (maybe) fighting crime like on Earth-38. Doubles from other Earths make for uncharted territory on Supergirl, so we're definitely excited to hear Andrew Kreisberg's reveal that they can pretty much go wherever they want after the success of the big crossover. Power Girl, as one example, could be a fantastic way to take a look at aliens of the multiverse.
The Power Girl of DC Comics is the Kara Zor-El of Earth-2, and it's there she fought for truth, justice, and the American way with her cousin, much the same as Supergirl and Superman on Earth-1. She ended up on Earth-1 during the Crisis on Infinite Earths storyline that obliterated most of the Earths in the multiverse, and she was stranded there for good when Earth-2 was destroyed. She distinguished herself both from the Earth-1 Kara and every version of Superman by updating her superhero name to Power Girl.
There are a few ways that Power Girl could make an Arrow-verse debut that would actually make a lot of sense. The second half of Supergirl Season 2 may be introducing the Legion of Super-Heroes of DC Comics fame; maybe Power Girl could be one of the members of the Legion down the road. Of course, the Power Girl of the comics is traditionally associated with the Justice Society of America, not the Legion of Super-Heroes. The Justice Society has been a major part of Legends of Tomorrow Season 2, though, so maybe Melissa Benoist could drop by Legends of Tomorrow to induct Power Girl into a J.S.A. rebirth. Who knows?
Unfortunately, Andrew Kreisberg's reveal to EW indicates that nobody on the Supergirl team has put any serious thought into introducing Power Girl just yet, assuming this is truth and not TV fibbery. But it doesn't necessarily have to be the comics' Power Girl that serves as the initial alternate Kara. Maybe Kara can just fiddle with her new inter-dimensional extrapolator and accidentally summon a completely different Kara from Earth-3, and maybe that Kara and Jay Garrick are friends...or enemies.
Personally, my fingers are crossed that if any version of Power Girl that makes it into the Arrow-verse, she gets a costume update. The white leotard is pretty iconic to the comic character, but the hole in the front that can really only be described as a "boob window" isn't the most empowering (or practical) for a character known as Power Girl, especially in The CW's non-exploitative DC Universe.
Supergirl is currently on its winter hiatus until 2017, so be sure to check out our midseason TV premiere schedule to see what you catch on the small screen in the not-too-distant future.