Quick history lesson for you: Supergirl's had a bunch of different origins in the comic books, but the one they always keep going back to is that she's Superman's cousin, and was also rocketed away from Krypton before it exploded, but for some reason it took her a little longer to make it to Earth. After that, she had a pretty similar deal to Kal-El: raised by a kindly family, secret identity, etc. The Supergirl show is looking to go all-in on that origin, too, meaning this will be the only one of CBS's roster of cop shows where the main character is an alien from a dead planet who's related to the most powerful superhero going. That's...interesting. And her Kryptonian heritage isn't going to be a small thing either. Especially because theatrical actor Laura Benanti has been cast as Alura Zor-El, Kara's birth mother whose wisdom and guidance proves invaluable in Karas journey toward becoming Supergirl. So whilst it's unknown if Superman himself will ever make an appearance during the show's run, he's very much on the table, and audiences will not doubt recognise the familiar backstory.