Girl power is back on The CW's Thursday night. Laura Vandervoort flies into Smallville as Supergirl, Clark Kent's (Tom Welling) strong-willed cousin from Krypton. Over in the land of demons, Katie Cassidy and Lauren Cohan join the war on Supernatural. Smallville airs Thursdays (8:00-9:00 p.m. ET), followed by Supernatural (9:00-10:00 p.m. ET).

On Smallville, the seventh-season premiere kicks off on Thursday, September 27 with the arrival of Kara, A.K.A. Supergirl, played by Laura Vandervoort. Born and raised in Toronto, Vandervoort recently appeared on the television series CSI and the feature films Troubled Waters and The Lookout. Armed with a second-degree black belt, Vandervoort soars into Smallville, catching the eye of both young photographer Jimmy Olsen (Aaron Ashmore) and budding-villain Lex Luthor (Michael Rosenbaum).

"We cast Laura because she is the embodiment of Supergirl -- she has warmth, beauty and she can kick some serious ass," says Al Gough, executive producer for Smallville.

This season, Sam (Jared Padalecki) and Dean (Jensen Ackles) Winchester get some help fighting evil in the form of two tough-as-nails female hunters. On Thursday, October 4, Ruby, played by Katie Cassidy, the daughter of 70s teen idol and singer David Cassidy, joins the hunt for the masses of demons who escaped from Hell in the second season finale. Cassidy was most recently seen in the feature film Click, with Adam Sandler, and has signed on to play Lucy Ewing in the big-screen remake of the hit series Dallas. Additionally she had a recurring role on 7th Heaven, and guest-star turns on "The District" and "Sex, Love and Secrets." On Thursday, October 18, Lauren Cohan enters the fray as Bela, a mercenary who realizes there is a lot of money to be made in the supernatural world. Cohan's feature film credits include Casanova, with Heath Ledger and National Lampoon's Van Wilder: The Rise of Taj and "Young Alexander the Great."

"Ruby and Bela, each in their own unique way, are dangerous, ruthless, more bad than good; and they'll each prove big trouble for Sam and Dean," says series creator and executive producer Eric Kripke. "We were excited to find both Katie and Lauren; they just popped off the screen for us, and they bring charisma and intelligence to their roles."

Reinterpreting the Superman mythology from its roots, Smallville was developed for television by Alfred Gough & Miles Millar based on the DC Comics characters.

Dont't forget to also check out: Smallville, Supernatural