Vampire Diaries (8pm, CW) - The third season begins with Elena and Damon searching for Stefan, who is with Klaus tracking a werewolf. Meanwhile, Caroline plans a party for Elena's 18th birthday, and Jeremy sees the ghosts of his late sister and his former girlfriend.
The Secret Circle (9pm, CW) - In this series premiere, teen Cassie Blake (Britt Robertson) moves to a new town, where she learns she is a witch and meets a circle of friends who inform her they are also witches. Adrienne's thoughts on this one, which is from New Bern native Kevin Williamson ("Vampire Diaries").
Project Runway (9pm, Lifetime) - The contestants are introduced to nine men on the runway, and then discover they must design for the men's significant others. Actress Malin Akerman is the guest judge.
It's Always Sunny in Philadelphia (10pm, FX) - In the Season 7 premiere, Frank wants to marry a prostitute and the gang can't talk him out of it. While Dee tries to burnish the hooker's heart of gold, Charlie tries distracting Frank by fixing him up with another woman. Also, Mac has put on a lot of weight.
Archer (10:30pm, FX) - Tonight is part one of a three part episode episode arc leading up to the show's official third series launch in early 2012. Tonight, Archer, in hiding since the murder of his fiancee, is finally tracked down in the South Pacific by handsome adventurer Rip Riley. To get Archer safely back to ISIS, Riley will have to survive the elements, a plane crash, a shark attack, starvation, drowning, exposure, and possibly pirates. And of course, Archer.