Kara Danvers (Melissa Benoist) and her allies will face past foes in upcoming episodes of "Supergirl" Season 2. Livewire (Brit Morgan) and Metallo (Frederick Schmidt) are returning to terrorize National City.

"Supergirl" executive producer Ali Adler told TVLine that more "fan-favorite" villains will come back in Season 2. Further announcements, however, are to be made.

Livewire, who's also known as Leslie Willis, first appeared in the fourth episode of "Supergirl" Season 1. A former employee of CatCo Worldwide Media, Leslie transformed into the supervillain Livewire after she got struck by lightning.

Leslie and Cat Grant (Calista Flockhart) weren't in good terms and the former vowed to end her former boss' life upon gaining powers but got thwarted by Supergirl. Teaming up with Siobhan Smythe a.k.a. Silver Banshee (Italia Ricci), Livewire reappeared last year to destroy Supergirl and The Flash (Grant Gustin).

Fortunately, the metahumans lost to their fight with the superheroes and got incarcerated. Although, it appears that Livewire will be on the loose again in the remaining episodes of "Supergirl" Season 2.

The international assassin Metallo (a.k.a. John Corben), meanwhile, appeared in Season 2's first two episodes. He was hired by Lex Luthor to kill his adoptive sister, Lena (Katie McGrath), but things didn't go according to plan after he got fatally shot. Project Cadmus got hold of Corben's body and modified him into the cyborg Metallo.

The returning villains don't stop at Livewire and Metallo. "Supergirl" executive producer Andrew Kreisberg recently revealed at the Television Critics Association press tour that Parasite (William Mapother) will come back in episode 13 of Season 2 after his debut in episode six, Collider reported.

Parasite was originally a scientist named Rudy Jones before he got infected by an alien parasite. The infection turned him into an alien-human hybrid that's capable of draining his fellow aliens' -- Supergirl and J'onn's (David Harewood) -- life energies.

The Girl of Steel, however, regained her powers and destroyed Parasite with the help of Mon-El (Chris Wood) and the Guardian (Mehcad Brooks). It's interesting how Parasite would return to National City since he got pulverized into dust after absorbing the radioactive element Plutonium 239.

"Supergirl" Season 2 will return for its ninth episode titled "Supergirl Lives" on Jan. 23. In the episode, Kara and Mon-El investigate the disappearance of a woman named Izzy (Harley Quinn Smith) against Snapper Carr's (Ian Gomez) wishes, SpoilerTV reported.

During their probe, Kara and Mon-El got sucked by a portal to another planet called Slaver's Moon where slavery is rampant. The planet has its own red sun, which renders Kara and Mon-El's powerless

What do you think of the villains returning to "Supergirl?" Share your thoughts below!

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Tags Supergirl, Melissa Benoist