This new and super girl will shake things up next season.
Per T V Guide
Look, up in the sky: It’s a bird… It’s a plane… It’s Supergirl?! When Smallville returns for its seventh season this fall it will be revealed that Clark Kent (Tom Welling) is not the only member of his family to survive the destruction of the planet Krypton. His cousin Kara “was sent to Earth in a ship that arrived at the same time as baby Kal-El’s,” reveals executive producer Al Gough, referring to Clark by his Kryptonian name. “But there was a problem and she’s been in suspended animation for the last 16 years. We’ll find out in the season premiere that the big dam break in last season’s finale is the reason she’s finally awoken.”
Gough says this latest visitor from the DC Comics universe “will help Clark get in touch with his Kryptonian roots. With his [adopted] father dead and his [adopted] mother moved to Washington [to become a U.S. Senator], and Lana blown up, suddenly there’s some family in his life.”
Like her cousin, Kara will have enhanced physical abilities generated by Earth’s yellow sun. “She has all of Clark’s powers and a couple he doesn’t have yet,” Gough teases. “She can fly. And her response when Clark asks why is “obviously girls mature faster than boys."
Kara, a teenager when Krypton exploded, was sent to Earth by her father, Zor-El (Kal-El’s uncle), to look after her younger cousin. But while in suspended animation she didn’t age and now it’s Clark who must be the mentor. “She becomes enamored with our culture: clothes and iPods and stuff,” Gough says. “We’ll have a lot of fun as she gets acclimated.”