“The Big Bang Theory” (8 p.m., CBS): “Dollhouse” may have gone up in flames,

“The Big Bang Theory” (8 p.m., CBS): “Dollhouse” may have gone up in flames, but Eliza Dushku is still getting work. Tonight she plays an FBI agent on “The Big Bang Theory.”

“30 Rock” (8:30 p.m., NBC): On “30 Rock,” Jack (Alec Baldwin) tries to placate Avery by setting boundaries in his relationship with Liz (Tina Fey).

TV Listings, B6