Back in September we got the news that a Supergirl show was given a full series order from CBS and that the man behind Arrow and The Flash, Greg Berlanti and Chuck and No Ordinary Family producer Ali Adler would be running things. The premise is rumored to focus on Superman's cousin, Kara Zor-El, as she begins to use her powers that she'd been hiding for years. Now The Wrap is reporting that casting has begun and that Claire Holt best known as Rebekah on The Vampire Diaries and The Originals is up for the title role.

It was also mentioned by Berlanti, in a recent interview with EW that Supergirl may exist in the Arrow and The Flash universe:

Are you guys excited for another DC Universe television show? Would you want Supergirl showing up on a future episode of The Flash or Arrow? Could this be the television version of a new Justice League trinity replacing Wonder Woman, Batman, and Superman on the small screen?