TV's former Superman Dean Cain and one-time Supergirl Helen Slater have been added to the cast of the new Supergirl series, starring Glee's Melissa Benoist as Kara Zor-El.

Cain, who played Supergirl's cousin in Lois & Clark: The New Adventures of Superman, and Slater, who also portrayed Superman's mom in TV drama Smallville, have landed mystery roles in the new TV superheroine series.

The news comes a day after Homeland's David Harewood and Grey's Anatomy regular Chyler Leigh were added to the cast, which also boasts Calista Flockhart, Laura Benanti and Mehcad Brooks.