Update as of 4/22: TV Line has confirmed that Gibbon's casting on Supergirl is valid. He will be guest starring as General Zod on the show's season 2 finale.
The reason for Zod’s visit remains a mystery, but with the myriad conflicts currently unfolding on the show — including whatever Queen Rhea has up her royal sleeve — it really could be anything.
Mark Gibbon, known for his role on Man of Steel, is rumored to join the CW's Supergirl as General Zod. In the comics, the character is Superman's greatest nemesis from Krypton.
According to Bleeding Cool, the actor is currently filming his scenes on the set of the superhero series. No word yet from the producers if the casting is valid.
Previously, it was announced that Tyler Hoechlin will reprise his Man of Steel role in the upcoming season 2 finale (airing on May 22).
Head over to Supergirl Spoilers page for the latest news.