VIDEO : 'Supergirl' Season 4 Casts Agent Liberty

Supergirl's third season ended on one heck of a cliffhanger, and it looks like a new Smallville alum will help bring the show's new story to life. Sam Witwer has been cast on the hit The CW series, according to Entertainment Weekly. Witwer will be portraying the established DC Comics character of Agent Liberty, and will be appearing in a series regular role.