CBR had the scoop on this one:
Owain Yeoman will be playing 1970’s Superman villain Vartox on Supergirl TV show.
CBR has confirmed with WBTV that Owain Yeoman (“The Mentalist,” “Extant”) has been cast as DC Comics supervillain Vartox in CBS’ upcoming “Supergirl” series. Yeoman will appear as a guest star in the show’s pilot episode.
According to the official description of the role, “Owain Yeoman plays longtime DC Comics villain Vartox, an alien convict, who has been hiding on Earth for the past twelve years. After Supergirl’s emergence on Earth, Vartox seeks her out to ascertain her identity and do battle with her.”
Vartox first appears in Superman #281