The second season of Supergirl was a departure from the show's first season, both on-screen and off. Behind the scenes, Supergirl moved its production from Los Angeles to Vancouver, as a result of the show's move from CBS to the CW. Moving to Vancouver helped executive producer Greg Berlanti coordinate filming between Supergirl and his other superhero TV shows on the CW, but the show lost Cat Grant and Maxwell Lord when Calista Flockhart and Peter Facinelli, the actors who played those parts, didn't want to uproot themselves. The creative team put James Olsen at the helm of CatCo Worldwide Media and looked for new villains for Supergirl to fight.

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Season 2 had no shortage of villains. The Luthor family caused a ruckus for the first half of the season. Although Lena Luthor, Lex's sister, turned out to be a friend rather than a foe, her mother, Lillian, was hellbent on eradicating aliens on Earth. Later in the season, the Daxamites, namely Rhea, wreaked havoc in National City. The result of that disastrous battle was that Kara had to say farewell to the love of her life, Mon-El, who took off for parts unknown in outer space. CBR runs down what's in store for Season 3.

15 WHAT WE KNOW: MAGGIE SAWYER HAS LIMITED RETURN

The relationship between Alex Danvers and Maggie Sawyer, aka Sanvers, has been one of the most exciting developments on Supergirl. Fans took to the couple right away, 'shipping them like crazy. Plus, Floriana Lima, who plays Maggie, gained a rabid following, as most actresses on a genre show do.

However, those same fans and 'shippers were dismayed to hear that Maggie will have a limited role in Season 3. In May, executive producer Andrew Kreisberg announced that Lima is interested in pursuing other opportunities. That means that Maggie will only be a recurring character, and not a series regular, as many had hoped. Executive producer Greg Berlanti, speaking at a reunion panel for Everwood for the TCA, reiterated that they would love to have Lima in as many episodes as possible, but that her ambition is taking her elsewhere.

14 WHAT WE WANT: SUIT CHANGES FOR SUPERGIRL

During the Supergirl panel at SDCC, Melissa Benoist, who plays Kara Danvers, said that she heard rumors that her suit will be changing sometime in Season 3. She claimed executive producer Andrew Kreisberg wanted a big change, but that she is perfectly happy with her suit just how it is.

Supergirl's current suit is the iconic one shown in most comic book versions of the superhero, in striking blue and red -- just like her cousin's -- and sporting an athletic skirt and aerodynamic cape. However, other versions of Supergirl have had very different suits. Power Girl, from Earth-2 wears a very recognizable white suit, but the CW's version of Supergirl doesn't seem like she would be comfortable revealing so much cleavage. Superwoman has a suit that looks much more like Superman's. Maybe as Kara matures, so will her suit.

13 WHAT WE KNOW: ODETTE ANNABLE CAST AS REIGN

Supergirl will meet more than one new villain in Season 3, including Reign. Reign will be played by Odette Annable, who starred in the short-lived The Astronaut Wives Club. At the International Comic-Con in San Diego, Annable said that her character has her own unique agenda, one that may surprise fans of Supergirl.

Supergirl writer Jessica Queller said during a panel that Reign is a bio-engineered weapon, which mirrors her characters in DC Comics. In comic books, Reign is a Worldkiller created by Zor-El, before she was outlawed by the Kryptonian Science Council. Perhaps, like in the comics, Reign will attempt to recruit Kara in her bid to conquer Earth. Regardless of Reign's agenda, fans can be sure they will see an epic showdown between these Kryptonians.

12 WHAT WE WANT: NEW SUIT FOR GUARDIAN

In addition to the rumor floating around about changes to Supergirl's suit, some talk has filtered through the media that the Guardian could be getting an upgrade as well. James Olsen didn't suit up as the Guardian until the second season. His first attempt at being a nighttime vigilante saw him wearing little more than a black ski mask and a black leather jacket.

It wasn't until Winn Schott discovered Olsen's secret that the Guardian became an armored menace. Actor Mehcad Brooks has said that he has difficultly seeing out of his helmet. Maybe Winn gives the Guardian a sleeker, more functional look in Season 3. Or maybe the Guardian gets some Iron Man-like modifications, with weapons stowed inside his suit. Regardless, the Guardian and Schott have more experience fighting crime, which should make them a more effective team this season.

11 WHAT WE KNOW: ADRIAN PASDAR CAST AS MORGAN EDGE

Casting Adrian Pasdar on Supergirl is a stroke of genius. The actor is a favorite of fans who watch genre TV. He previously starred on Heroes as Nathan Petrelli, who had the ability to fly. He has also been chewing up scenery on Agents of S.H.I.E.L.D. as General Glenn Talbot. Now, on Supergirl, he'll guest-star as Morgan Edge, a cunning real estate developer who finds himself pitted against not only Supergirl, but also Lena Luthor.

In the comics, Morgan Edge owns Galaxy Communications, which is the Daily Planet's competitor. He also has connections to the interstellar crime syndicate called Intergang, which makes him a servant of the evil Darkseid. There's no news as to what Edge's agenda will be on Supergirl, but it can't be a coincidence that he shows up in National City at the same time as Reign, a Kryptonian.

10 WHAT WE WANT: JAMES OLSEN'S LOVE INTEREST

In just one season, James Olsen got his heart broken twice. During the first season of Supergirl, he tried to make his relationship with Lucy Lane work, only to realize that he was in love with Kara. Once Lucy figured that out too, she dumped him. Then, just when it looked like he and Kara were cleared for take-off, Kara gave him the "I need to focus on myself" speech.

Olsen didn't pursue romance at all during the second season, instead choosing to fight crime in his off-hours. In Season 3, however, Olsen will get another shot at having a love-life. At SDCC, both Mehcad Brooks, who plays Olsen, and writer Jessica Queller said that Olsen will be partnered with a new girl this season. Whether that girl is someone we've already met remains to be seen.

9 WHAT WE KNOW: YAEL GROBGLAS CAST AS PSI

The CW announced that Yael Grobblas, who stars on the network's comedy Jane the Virgin, will play Psi, another new villain on Supergirl. To date, Supergirl has relied mainly on Superman villains to fill their roster of bad guys. However, Psi is a Supergirl villain from way back.

Psi is a telepath whose real name is Gayle Marsh. She was taken in and trained by a scientist named Daniel Penderghast, who wanted to use her power to stop the decay he saw in the world. In the original story, Psi ran into Supergirl's alter ego and, thanks to her immense mental powers, realized that something was very different about her. Not much is known about Psi's appearance on the TV show. However, several photos of Grobblas dressed in head-to-toe black leather have showed up online.

8 WHAT WE WANT: RETURN OF MISS MARTIAN

M'gann M'orrz showed up on Supergirl working in an underground bar for aliens, which should have been a tip-off to anyone who met her that maybe she wasn't who she said she was. Soon enough, she revealed herself to be a Martian. Then, she revealed herself to be a White Martian.

After some fighting and near-death experiences, M'gann and J'onn J'onzz came to be friends, if not paramours. Miss Martian also became a fan-favorite, because in his scenes with her, Martian Manhunter shows sides of his personality the audience doesn't always get to see. David Harewood, who plays J'onn J'onzz, told fans at SDCC that he's looking forward to working with Sharon Neal again. Does that mean fans can expect to see Miss Martian in Season 3? Whether she will be part of the storyline, or merely a vision, remains to be seen.

7 WHAT WE KNOW: CARLY LUMBLY CAST AS M'YRNN J'ONZZ

Although J'onn J'onzz has revealed himself as a Green Martian on Supergirl, and he's told his co-workers a little about the death of his family on Mars, not much else is known about him. He stays focused on his work at the D.E.O. Although he occasionally shows affection to the Danvers girls, who he has sworn to protect, he is mostly a stoic guy.

In Season 3, though, we will find out more about J'onn and his background in scenes with his father. Carl Lumbly has been cast as M'yrnn J'onzz, J'onn's father. No doubt J'onn will be ecstatic to learn not only that there is another Green Martian still alive, but also that he is not the last member of his family to survive his planet's genocide.

6 WHAT WE WANT: TO KNOW MON-EL'S FATE

Last we saw Mon-El, he was climbing into a spaceship to fly away from Earth, where he would be killed with any remaining Daxamites if he stayed. He and Kara shared a tearful goodbye before he disappeared forever. However, the audience watched as Mon-El was sucked into a wormhole or Boomtube or something, which means that we haven't seen the last of Daxam's prince.

How Mon-El returns to Supergirl remains a mystery. Chris Wood, who plays Mon-El, attended the International Comic-Con in San Diego, and he was as tight-lipped about Mon-El's return as the showrunners. He hinted that, wherever Mon-El wound up, he continued maturing and becoming more of a hero. He implied that Mon-El might have even earned his own superhero suit, thanks to whatever he's been up to before he returns.

5 WHAT WE KNOW: CALISTA FLOCKHART RETURNS

When Supergirl's production moved from Los Angeles to Vancouver, where the CW's other superhero TV shows are filmed, there were inevitable changes to the show. Perhaps the biggest change, and the one that upset fans the most, was saying goodbye to Calista Flockhart as Cat Grant. The network explained that Flockhart wasn't interested in moving so far away, which meant Cat Grant handed the reins of CatCo to James Olsen and left for parts unknown.

Happily, Flockhart returned for the last two episodes of Season 2, when Grant not only played a pivotal role in saving National City, but also revealed to the audience that she knows Supergirl's true identity. At SDCC, showrunners thrilled Supergirl fans when they revealed that Cat Grant will appear in the Season 3 premiere, and will be a recurring character this season.

4 WHAT WE WANT: A NEW LOVE INTEREST

Like any young woman, Kara Danvers has experienced a lot of ups and downs in her romantic life. While she nursed a crush on James Olsen, and ignored Winn Schott's innuendos, she briefly dated Cat Grant's son, Adam Foster. Finally, she shared a few smooches with James, only to kick him to the curb to focus on being Supergirl.

Her new mission didn't last long, however, after Mon-El crash-landed in National City. They dated, and after she reined in his more selfish tendencies, the two of them fell in love. Now that he's off in outer space, Kara is left alone again. Although actress Melissa Benoist told fans at SDCC that Kara needs to be alone for a while, she is an attractive, powerful, single woman. It's very possible someone else will take Mon-El's place, even if it's only briefly.

3 WHAT WE KNOW: ERICA DURANCE CAST AS ALURA

For two seasons, Laura Benanti played Alura Zor-El, Kara's biological mother. She also played the evil Astra, Kara's aunt, until she was killed. However, between Benanti's commitments to Broadway shows, co-starring on Detour, appearing as Melania Trump on The Late Show with Stephen Colbert and working on upcoming projects, the actress is too busy to reprise her role on Supergirl.

The CW, in another stroke of casting brilliance, called on an actress from the DCEU to take Benanti's place. Erica Durance, who played Lois Lane on Smallville for seven seasons, will play Alura in Season 3. During the Supergirl panel at SDCC, fans caught a glimpse of her in the teaser trailer (pictured above). The CW is fond of casting actors and actresses from the DCEU in Supergirl, including Dean Cain as Jeremiah Danvers, Teri Hatcher as Rhea, Lynda Carter as President Olivia Marsdin and Helen Slater as Eliza Danvers.

2 WHAT WE WANT: LENA AND KARA'S SECRET

Just like her cousin, Kara wears eyeglasses to protect her identity as Supergirl. Although a few people in National City have guessed her secret -- including Max Lord and Cat Grant -- Kara has almost everyone fooled, like Lena Luthor, one of her best friends. But how long can her charade last?

Since Lena's appearance on Supergirl, fans have been waiting to see if she will become the villain her brother, Lex, was. Fans have also been wondering if Lena and Kara will become close enough friends for Kara to let Lena in on her secret. Katie McGrath, who plays Lena, told fans at SDCC that she hopes Lena never finds out who Kara really is. McGrath likes that Kara doesn't have to be Supergirl around Lena, and she likes that Lena can be vulnerable around Kara. Perhaps Kara revealing her true identity would be the push Lena needs to turn against her.

1 WHAT WE KNOW: KARA WILL FOCUS ON SUPERGIRL

"Kara Danvers was a mistake." That's what Supergirl says in the teaser trailer for Season 3. She just said goodbye to her boyfriend, who she thinks is gone forever. She also had a pretty rough year battling Lillian Luthor and Rhea. Plus, who wants to find out their boyfriend's mom hates them? When Supergirl says Kara was a mistake, she really means that her human feelings, not evil villains, are too much to bear.

Melissa Benoist explained to fans at International Comic-Con that, in Season 3, Supergirl will focus on being a superhero and will turn away from being Kara Danvers, an intrepid reporter and all-around nice girl. It sounds like she's looking to drown her sorrows in some punching and kicking. Like any great hero, however, her time on the dark side will, no doubt, lead her back home.

Supergirl Season 3 will premiere on the CW on October 9, 2017. What are you looking forward to? Tell us in the comments!