A candid set photo posted to Imgur seems to have revealed the identity of the villain that may urge Supergirl to team up with the Flash. The CW's Scarlet Speedster will make a guest appearance on CBS' "Supergirl" in March, and when he does, he might go up against Silver Banshee.

The photo shows Grant Gustin in the foreground, casually rocking his Flash pants; part of Melissa Benoist can be seen in her Supergirl suit behind Gustin, as she crouches down to greet a young fan. And even further in the background sits... Silver Banshee.

The villain's unmistakable appearance can be seen in the background, relaxing in a chair on set. Silver Banshee's appearance on "Supergirl" has been coming for a while; Italia Ricci was cast as the villain in December and the actress appears -- in human form -- in the promo photos for "Supergirl's" February 22 episode.

The official character description from December reads: "Italia Ricci is joining the cast of Supergirl as Siobhan Smythe, Cat Grant's latest hire who at first becomes a work nemesis for Kara. But she later proves a more deadly foe for Supergirl when she takes on the mantle of DC Comics villain, Silver Banshee."

Italia Ricci debuts as Siobhan Smythe in the February 29 episode of "Supergirl"; the "Flash" crossover episode of the series airs on March 28 at 8 PM on CBS.