Was That Our First Look at Reign on 'Supergirl?'
Reign
For DC Comics fans, something about that face definitely looks familiar - namely, it's resemblance to the comic book version of Reign, the season's Big Bad.
Annable is set to play the maniacal Worldkiller, and fans already got a glimpse of her tonight - but as her more human-like persona, Samantha. With her set to transform into the villain over the course of the season, could this have been a look at what her final form?
Possibly. While it would make sense to plant the seed of her Reign persona already, unveiling it with Alura doesn't necessarily line up. Sure, both hail from the same planet, and they could be tied together more than we currently believe, but it's just too early to tell.

A Different Worldkiller
So if the face ends up belonging to a Worldkiller, could it be someone other than Reign?
If you're not familiar with Reign or Worldkillers, you're likely not alone. Introduced in 2012, Reign's history is a mystery even to her. She knows her name, that she's a Worldkiller and not much else. As for Worldkillers themselves, in comics they're bloodthirsty, uncontrollable, super-powerful biological weapons created on Krypton who are, as the name Worldkiller implies, a threat to all living beings.
Five of these Worldkillers survived the destruction of Krypton, including Reign and as we saw at the end of last season, she was sent to Earth in a pod, much like Supergirl herself.
Annable recently hinted that more Worldkillers could enter the fold at some point, meaning it's certainly within the realm of possibility. And considering the technical effects that would go into bringing some of the more colorful comic book Worldkillers to life, it would make sense for them to follow the same sort of grey-and-black aesthetic.

Doomsday
Another option, albeit probably a less likely one, would be a version of Doomsday.
The evil alien creature is best known from Superman media, largely thanks to films like Batman v. Superman: Dawn of Justice. But it's hard to deny that a version of Doomsday could work on Supergirl, as the show has enough variables at play to make it happen.
If you swapped out Lex for Lena, and another Kryptonian for Alura, you could easily translate the BvS origin of Doomsday onscreen - or at least a version of it. It would also create a hell of an emotional arc for Kara, if she had to fight a villainous version of her long-lost mother.

Whoever Owns That Ship
And finally, there's that conundrum of the mystery ship shown underneath National City's waters at the tail end of the episode.
A couple different alien races from the pages of DC Comics could be at play here, including the Coluans and the Durlans. Granted, we've already seen a pretty noteworthy Durlan in President Marsdin (Lynda Carter), but there could be a narrative reason as to why this alien looks so different.
But again - why would that alien be tied to this vision of Alura? Supergirl fans will just have to wait to find out.
