The third season of Supergirl has arrived, which means that it's time to learn more about the new villains that the Girl of Steel will face in future episodes.

The TV version of Kara Zor-El has already battled it out on television with many villains from Supergirl's comic book universe, including Bizarro Supergirl, Livewire, Dollmaker, Metallo, Silver Banshee and Red Tornado, so who's next?

The CW recently announced that one of those new villains is Reign, a character taken from the New 52 universe of DC Comics. Portrayed by Odette Annable, Reign is a mysterious villain who didn't really appear much throughout the Supergirl comic book series.

But who exactly is Reign and how will her presence on the series affect Supergirl? Is she the yang to Kara's yin? Is she an alien or a human? Is she someone that the world needs to watch out for?

One thing is for certain: The CW teased Reign at the end of the season two finale. In that final scene, viewers got a look at a third pod sent from Krypton. So here's more information on what viewers can expect from the character.

Here are Supergirl: 15 Things You Didn’t Know About Reign.

 She first appeared in Supergirl #5 - Homecoming

In Supergirl Vol 6 #5, Supergirl set off to find whatever is left of her planet Krypton, in a desire to return home. She leaves Earth without even knowing if she can return after, but she has a need to see what is left of her home plane.

What she doesn't realize is that someone followed her to Krypton. She ends up discovering what is left of Argo City, a place ripped from the planet's surface and left to float in the vast reaches of space. She finds a message from her father, determining that Krypton is, in fact, completely gone.

Supergirl becomes upset and starts smashing up the ruins, but runs into Reign, who asks Kara to join her in her Worldkiller mission.

She's a biological weapon

The first thing viewers need to know about Reign is that she is not human, although she appears humanoid. She is a biological weapon created by Kryptonian scientists, something known as a Worldkiller. Her purpose is exactly what her name suggests: she can destroy worlds. Think of her as a walking and talking Death Star.

The Worldkillers are bloodthirsty and they hunger for destruction, making them extremely dangerous. But the Worldkillers, including Reign, were still allowed to exist. And now on the Supergirl TV show, Reign is living on Earth, apparently having been sent there just before Krypton exploded into nothing.

Much like Supergirl, Reign has superhuman strength, but she's probably the stronger of the two. She can also survive almost anything and can fly.

She was eventually outlawed by Krypton

Although it was Kryptonian scientists that created the Worldkillers, including Reign, those scientists eventually realized that these biological weapons were far too dangerous. The Worldkillers seemed to have minds of their own, after all, and their unending thirst for destruction made them unpredictable and not easily controlled.

"How do I know so much about the Worldkillers?!" Reign says in the comic books. "Because I AM one. Born to fight. Born to slaughter. Born to conquer. The desire burns in me like a million suns. But I do not know why."

Needless to say, that insane desire to slaughter and kill made the Kryptonian science council a little nervous, so they eventually banned Reign and the other Worldkillers, although the scientists did not kill their creations.

Kara's dad created her

The House of Zor-El might seem perfect on the surface, as does Krypton, but they were ultimately a lot like most of humanity: flawed in many ways.

Something that Supergirl viewers might not know is that her father, Zor-El himself, was a scientist. But he wasn't just any scientist; he was the scientist that originally created the Worldkillers, including Reign. That's right, Supergirl's dad created the ultimate killing machine that Kara had to fight in the comic books to keep Earth from being completely destroyed.

Sure, the Kryptonian science council eventually outlawed that research, but by then, it was too late. One must also wonder why the science council didn't kill the Worldkillers, although it's possible that they are indestructible, considering their nature. Way to go, Zor El.

She's more naive in Supergirl

In the Supergirl comic books, Reign knows exactly who she is and what her purpose is. But the Supergirl television series plans on taking a different approach to the character. On the show, Reign came to Earth in a pod as a child, just like Kara, but although Kara knew who she was growing up, Reign did not.

As far as Reign knows, she's a human named Samantha Arias. Season three of Supergirl will show Reign as she grows to learn what she really is.

“Everyone [in the cast] will have a relationship with her, and that will drive much of the season in terms of how far they’re willing to go to stop her when she becomes Reign,” Supergirl executive producer Andrew Kreisberg said to TV Insider. “Some will believe she needs to be saved; others will think she needs to be stopped.”

Raised by adoptive parents, just like Supergirl

The Supergirl television series will draw a lot of parallels between the lives of Kara Zor-El (aka Supergirl) and Samantha Arias (aka Reign).

Both came to Krypton as young children, sent in pods to escape the destruction of that planet. Both grew up among humans. Both lived normal lives and somehow ended up in National City. Both had adoptive parents.

What's most interesting, though, is that the show will have Reign not knowing who she is or where she comes from, so she'll have to deal with that fact when she discovers that she's a destructive killing machine.

The series will probably also delve into the drama involved when she tries to balance this new knowledge with the only life she has ever known.

 In the TV series, she has a daughter

The Supergirl television show writers plan on making Reign's life even more complicated. Although the Reign in the comic books did not have any family, the TV show will bring more drama through by giving Samantha a daughter.

This will, obviously, create a lot of conflict once Samantha discovers what she is. Not only is she a single mother, but her daughter is half-human and half-Kryptonian biological weapon.

“When we meet Reign, she’s just a woman,” executive producer Andrew Kreisberg said to ComicBook.com. “Her name is Samantha and she’s a single mom, and she has no idea that she is Reign; she has no idea that she was the baby in the pod at the end of last season, so the journey that she takes this season is watching her realize her heritage and see[ing] how it manifests.”

Reign is not the only Worldkiller

The Kryptonian scientists were not content with just creating one ultimate destructive machine of death. Instead, they created an army of them.

Sure, these Worldkillers were eventually outlawed, and many did not survive the demise of Krypton. In the comic books, though, five did survive, although they woke up in the aftermath of the planet's death unsure of who they were and what their purpose was. They still had an insatiable need to destroy things, though, so they began to explore the galaxy searching for answers.

Reign discovered Kryptonians living on Earth and decided that's where the answers were, so she and her fellow Worldkillers landed there and attempted to conquer it. Fortunately, Supergirl did what she does best and saved the day.

There is no indication that the television series will bring in other Worldkillers, although Samantha's daughter is at least half Worldkiller.

She is only one of several survivors of Krypton

When Superman got his first introduction to comic books, most assumed that he was the only survivor from the planet Krypton after its destruction. But then other survivors appeared, including Superman's cousin, Kara, aka Supergirl.

On the television series, Kara's family sends her to Earth to look after her cousin, but she got trapped in the Phantom Zone and landed there after her cousin was already grown. So far, the series only has Kara and her cousin as Kryptonians who survived after the death of their planet, but at the end of season two, viewers saw a third pod leaving Krypton and heading to earth.

That third pod held Reign, who was apparently too young to remember anything about Krypton, as she grew up believing that she was human.

In the comics, she lost to Supergirl and retreated

In the comic books, Reign and her fellow Worldkillers arrived on Earth seeking out the answers to their existence, including why they feel the need to destroy everything that comes into their path. They lost their memories after the destruction of Krypton, but still had an insatiable lust for destruction, which they bring to Earth.

Reign led three of the Worldkillers across the planet in an attempt to wipe it out, and an exhausted Supergirl fought them, because that's what she does. After Supergirl managed to hurt one of the Worldkillers, Reign decided to retreat, unwilling to risk losing the only family she's ever known, the other Worldkillers.

Before she left, she issued a final warning to Supergirl and to Earth: she would return and face Kara again.

Her weapon of choice is a sword

Although Reign has superhuman strength that is probably greater than even Supergirl's, she still prefers to do some of her world destroying with a sword, as seen in a few panels of the Supergirl comic books.

Of course, the television show won't have Reign looking exactly like she did in the comic books, so who knows if the sword will ever put in an appearance on TV. But she will still be a formidable foe for Kara on the TV show.

Executive producer Kreisberg called the character "scary, powerful and heartbreaking" in an interview with The Hollywood Reporter. Expect a storyline that focuses not just on the Worldkiller aspect of Reign, but also the human side that grew up on Earth and now has a half-alien daughter.

She was part of the New 52 reboot

In 2011, DC Comics sort of rebooted its entire universe by introducing The New 52. This was in response to wrapping up the "Flashpoint" storyline that crossed many of the DC titles and gave the company a new jumping off point for re-introducing some of tis characters to new comic book readers. The company canceled all of its titles to make way for brand new ones, all of them part of this new universe.

Although The New 52 ended with the recent Rebirth reboot, many of those stories remain popular, including those involving Supergirl.

Reign was a character during The New 52 era of Supergirl comic books, and has not put in an appearance in any Supergirl story arcs since then. The TV series could prompt new interest in the villain, though.

The TV series will show how Reign becomes a villain

Throughout its first two seasons, Supergirl has featured a lot of villains, but the majority of them pretty much started out that way: they were always bad guys.

There hasn't been a lot of background information on the villains given, but the series' introduction of Reign will change that. Throughout the course of season three, viewers will go on a journey with the character as she slowly begins to learn that she is not the human she thinks she is.

"What I think is really special about this storyline is it’s a slow play and you’ll get to see this whole heartbreaking story unfold in a really — they’re taking their time with it, and we have the time to do it," Annable said to Entertainment Weekly. "I think the audience is really going to hopefully relate."

She left Supergirl for dead on Argo City

When Reign first awakened after the destruction of Krypton, she tried to get back to the planet. Confused and unsure of who or what she was, though, it surprised her to discover that the planet was gone. But she did find Supergirl and followed the hero back to what was left of Argo City, which was also the place of Reign's birth on the planet. Reign hoped to find out more there about who she was and why she had such a need for destruction.

There, Reign fought Supergirl, and won, proving that the Worldkiller was stronger than the Girl of Steel. She left Supergirl for dead among the ruins of Argo City and went to Earth to conquer the planet. Fortunately, Supergirl survived that encounter.

Her TV costume won't look like her comic book costume

It's already pretty obvious that Reign won't look exactly the same on the TV show as she does in the comic books. In the comics, she has a humanoid body, but her face and skin do not look like they would pass for human on Earth. The TV series actually created the character to appear human, so much that Reign herself does not know what she is: she believes herself a human.

Once she becomes a villain, though, she still needs a costume, but it won't be the bra and pants that comic book fans are already familiar with. That new costume probably won't appear for some time: the character has to undergo the whole arc from discovering she's a villain to dealing with it and taking on Supergirl.

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