Whether or not she goes looking for it, "Supergirl" is going to find trouble in the back-half of Season 2. TVLine reports that both Metallo and Livewire are scheduled to return to the show, as well as a few other fan favorite villains.

According to executive producer Ali Adler, Metallo and Livewire are just two of the villains who will be making their dastardly return in 2017. She also confirmed that other "fan favorite" villains would make an appearance, but couldn't offer any additional details as it was too early to make any confirmations.

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Played by Brit Morgan, former CatCo radio host Leslie Willis underwent a shocking transformation after she was struck by lightning in the appropriately titled Season 1 episode "Livewire." After waking up in the hospital, she discovered she had the ability to manipulate electricity and even travel through electrical devices. Taking on the name Livewire, she vowed revenge on Cat Grant for putting her in this position. She posed a real threat to Supergirl, as she could produce enough electricity to make the Girl of Steel's heart burst, but she was ultimately stopped by both Kara and Cat.

Livewire also appeared in "World's Finest," the first crossover between "Supergirl" and "The Flash." There, she teamed up with Silver Banshee in order to overpower Supergirl. However, they weren't counting on fighting the Flash as well. Together, Supergirl and the Flash were able to subdue and capture Livewire and Silver Banshee, before Flash returned to his world.

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On the other hand, Frederick Schmidt's Metallo debuted in the Season 2 premiere "The Adventures of Supergirl." He started out as a cruel mercenary hired by Lex Luthor to kill his sister Lena, who has taken over his company and renamed it L Corp. Lena then shot him, leaving him mortally wounded, which is just how Cadmus Lab found him. Cadmus saved him by giving him a Kryptonite-powered heart, making him a deadly weapon against Supergirl and her cousin Superman. Nevertheless, the Kryptonian cousins were able to defeat him together.

Starring Melissa Benoist as the Girl of Steel, “Supergirl” returns Monday, January 23 at 8 pm ET/PT on The CW. The series also stars David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott and features appearances by Calista Flockhart’s Cat Grant as well as Tyler Hoechlin’s Superman.