In September last year, it was officially announced that CBS has a series order for “Supergirl”, which is the cousin of Superman as she’s finally beginning to use her powers at age 24.
Produced by Warner Bros. TV and Berlanti Productions, “Supergirl” is an hour-long drama that centres on Superman’s cousin, Kara Zor-El, who arrives on Earth after escaping the destruction of Krypton. Just like her cousin, she was taken in by a foster family, the Danvers, who taught her to repress her superhuman abilities.
However, after many years of repressing her abilities, an unexpected disaster forces her to embrace her power to help the people in the city. At the age of 24, she becomes the hero she was meant to be: Supergirl.
“Supergirl” to see Melissa Benoist take lead role
Now, we all already know that CBS’ “Supergirl” will star Melissa Benoist (who is known for role as Marley Rose in “Glee”), as the iconic DC Comics heroine, who goes by Kara Zor-El on Krypton but Linda Danvers on Earth. The series’ co-stars have also been announced and they include the likes of Mehcad Brooks (of “True Blood” fame) as Jimmy Olsen, Laura Benanti (of “Nashville” fame) as Kara’s birth mom and, more recently David Harewood (of “Homeland” fame) and Chyler Leigh (of “Grey’s Anatomy” fame), who play a government agent and Kara’s foster sister, respectively.
But just a little earlier today, The Wrap reported that CBS has added Dean Cain and Helen Slater to its “Supergirl” drama, as confirmed by a spokesperson for Warner Bros. TV. The actors, who played Superman on “Lois & Clark: The New Adventures of Superman” and Supergirl in the film of the same name, are set to guest star on the pilot. Neither of their roles are known at the moment, but their making appearances should be a treat when the series finally debuts!
Source: flickeringmyth
In any case, oh hello there, Superman! Long time no see 
The pilot episode of the series will be written by producer of “Arrow” and “The Flash” Greg Berlanti and producer of “No Ordinary Family” Ali Adler. They will also executive produce the series alongside Sarah Schechter and Warner Bros. TV.
Sources: The Wrap.