'Supergirl' season 3 spoilers: EP teases new villain; Kara to don different costume

Facebook/TheCWSupergirlPromotional photo for The CW's "Supergirl"

"Supergirl" is introducing a new villain this season 3, according to the show's executive producer. The catch? The villain doesn't even know she's a villain yet.

Season 2 of "Supergirl" saw another pod escaping the destruction of Krypton. Inside that pod was Reign (Odette Annable), a bio-engineered weapon also known in that universe as Worldkiller.

"When we meet Reign, she's just a woman," executive producer Andrew Kreisberg told Entertainment Weekly. "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 how it manifests."

The comics portray Worldkillers as bloodthirsty and super-powered aliens bent on conquering Earth. Reign first appeared in Supergirl #15 in 2012 as part of The New 52.

Kreisberg also said that viewers are used to meeting a villain in the final episode or in one of the later episodes, realizing that it was that person pulling the strings all along. What isn't always shown, he explained, is how he or she becomes the big, bad villain.

"The thing that everybody is struggling with on 'Supergirl' this season is 'What does it mean to be human?'" Kreisberg added.

Reign's story is in line with the upcoming season's theme as Supergirl (Melissa Benoist) herself will be going on her own journey of self-discovery, having lost her love Mon-El (Chris Wood) after she saved the world in the season 2 finale.

Supergirl, also known as Kara Danvers, will have a very visual way of showing this journey of identity. Benoist hinted at a new outfit for the superhero in season 3.

"There is a different suit that I will be wearing at some point this season, but I won't tell you when or to what capacity," the actress said. "It's cool, though."

No further details have been revealed, but fans don't have to wait too long to find out. "Supergirl" season 3 premieres on Monday, Oct. 9, 8 p.m. EDT on The CW.