Leviathan is coming. Ahead of Season 5, Supergirl stars Melissa Benoist, Chyler Leigh, David Harewood, Mehcad Brooks, Jesse Rath, Nicole Maines, Andrea Brook and Azie Tesfai as well as executive producers Jessica Queller, Robert Rovner and Sarah Schechter offered a sneak peek into the Girl of Steel's next big challenge.

Lex Luthor himself Jon Cryer took the stage to moderate the panel.

"One of our big bads this season is Leviathan, so we're bringing that into our canon this year... This season is going to be about how technology effects us," Rovner explained. "We'll be seeing how our villains this season use technology against us and how our heroes bring us back."

"The character I played died, which is really sad, because I don't know if you know anything about comics, but if a character is dead, they're dead," Cryer joked.

"Lex Luthor is coming back," Rovner confirmed, then addressed Cryer. "We're excited to have you back. Hopefully you can stick around."

She announced Julie Gonzalo  as Andrea Rojas (aka Acrata), the new head of CatCo, and Staz Nair as original character William Dey, who will act as a foil to Kara.

"This is a character that will be joining the show this season, something that I've been pitching since I got the role," Rath announced. "You can't talk about Brainy without talking about his family... my real-life sister will be joining the show, Megan Rath. She will be playing a female Brainiac-5."

"You leave right when I get there," Cryer said to Brooks.

"I've been here since day one and I can honestly say that I've never done a series before that this many people have been on the series for this long," Brooks shared, tearing up. "They're my family. I'm just proud with what we were able to accomplish the past few years. I didn't grow up being able to see a superhero that looked like me, like at all... and then we actually dealt with racism and put it in the context of bullying... Thank you."

"We're so proud to have had him on the show," Schechter said.

"It's really weird and I can honestly hardly believe it's been a year since I've been on this panel," Maines said. "This past year has been so insane and unbelievable... just the past season of being able to become this superhero for me, personally, was so amazing and I was so fortunate to get to have these cool powers and have this cool suit and work with cool people and tell awesome stories... This is my first trans superhero too... I'm just so happy."

"That was obviously a big story to tell, and it is something that will be explored and we wanted to do very delicately, something we want to treat very respectfully," Leigh said of Alex's storyline. "To know that you'e with somebody that feels the same way and has the same dreams... everything is at risk and at stake at all times... we talked about this at length, the process of adoption and how realistic what happened in the show is... We wanted to keep the authenticity of Alex's story... She needed somebody to be able to talk to, and Kelly coming into the picture was the perfection place to introduce the like-mindedness... That is very much a part of Alex's desire... it's going to be really exciting to see what that looks like... We're very much on the same page to make sure things are really cool."

"As a woman, being a mother is such an incredible privileged," Tesfai added. "It is a voice that doesn't go away, and adoption is not a linear experience... so many women are going through that."

In addition to Benoist's directorial debut, Harewood will direct the 11th episode of the season.

"I'm a little terrified," Benoist said of her upcoming directorial debut. "I don't how much I'll be in the episode I end up directing, but I'm trying to get as prepared as I can... we have an amazing crew, like the best crew." She revealed she has been shadowing Jesse Warren.

McGrath addressed Luthor's death and impending resurrection. "That was hard for me to do, and now they're bringing you back," she said. "You've committed murder and your world is done and how do you let everybody know how mucht that's destroyed you?"

"I just kept talking. I got shot and I just kept talking. There was more, by the way. I had about another paragraph and a half," Cryer pitched in.

"You were very patient with me on that day," she added. "We are very lucky on this show."

"When I first showed up, I figured I was a comic relief, I would do a couple episodes and that would be that," Andrea Brooks recalled. "She has a thing for bad men... She truly is an onion, and she just keeps unraveling and unraveling... she is, in fact, a triple agent... getting to work with Lex Luthor, once you showed up... that was a dream."

As to Lena's discovery of Kara's secret identity, Benoist said, "I don't want her to, and Kara would certainly not want her to, and I think she'll fight tooth and nail... if she saw someone going down a path like Lex Luthor's."

"She is ultimately just human. She's flawed. She's brilliant. Ultimately, she just wants to do the best she can," McGrath added. "She has been given this horrible news... the question for Season 5 is does that define who she is?"

Asked about the introduction of a plus-sized hero, Queller replied, "Soon. It's a good point, and point well-taken."

Returning Sunday, October 9 at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen and Chyler Leigh as Alex Danvers.