30 Rock (8pm, NBC) - Political satire at "TGS" drives a wedge between Liz and Jack. Elsewhere, Liz and Criss spice up their relationship, and Jenna is demoralized by the sluggish sales of her summer dance song.
Last Resort (8pm, ABC) - A search for three missing crew members leads Chaplin to Serrat's compound. Meanwhile, Sinclair and Shepard hold a secret meeting.
The Vampire Diaries (8pm, CW) - Season 4 begins with Elena (Nina Dobrev) waking up after her car accident and realizing she died with vampire blood in her system. Now she must go through the horrible transition to become a vampire, or she must die.
Beauty and the Beast (9pm, CW) - In this retelling of the classic fairy tale, a homicide detective teams with a man who takes on incredible but uncontrollable strength when he's enraged. Adrienne reviews.
Vice Presidential Debates (9pm) - The debate between Vice President Joe Biden and Rep. Paul Ryan, live from Danville, Kentucky, will air on ABC, CBS, NBC, UNC-TV, Fox, Fox News, MSNBC and CNBC.
Project Runway (9pm, Lifetime) - In part 1 of the 2-part finale, the remaining contestants return from hometown visits to present three looks to judges.
It's Always Sunny in Philadelphia (10pm, FX) - In the eighth season premiere, Dennis and Dee must make a life-or-death decision about their ailing grandfather. Meanwhile, Mac, Charlie and Frank discover that the old man used to be a Nazi.
The League (10:30pm, FX) - In the fourth season premiere, preparations are made for the arrival and Kevin and Jenny's baby, and Taco is invited to the Dallas Cowboys' training camp.
Brand X With Russell Brand and Totally Biased With Kamau Bell also return to FX tonight, at 11 and 11:30 respectively.