Big Brother Big Brother

Big Brother 12
8/7c CBS
If the Brigade alliance continues to hold strong, then Ragan will be leaving the house tonight and the final four houseguests will be Britney, Enzo, Hayden and Lane. But the once-mighty Brigade is beginning to show some cracks. Brigade buddies Enzo, Lane and Hayden jettisoned fourth member Matt last week, and Enzo and Hayden are fearful of Lane's friendship with Britney. They also believe that Lane is rich and doesn't need the $500,000 top-prize money. Tonight's vote isn't the most crucial thing. The Head of Household competition that follows is critical. If Britney wins, the Brigade could be history. — Tim Holland

American Chopper: Senior vs. Junior
9/8c TLC
Has the time finally come for Sr. and his sons to put their long-running family feud behind them? It is possible that a reconciliation is in sight after a serious accident at Paul Jr. Designs prompts the patriarch to put his differences with them aside and reach out to Jr. and Mikey. Meanwhile, the OCC crew members set out to build a bike that's "out of this world" for the Science Channel's "Meteorite Men." — Karen Andzejewicz

Project Runway
9/8c Lifetime
Couture clashing and couture shock overflowed in the previous episode when the group split into two teams to fashion a cohesive line. What we ended up with was Gretchen being bossy, Casanova having a diva moment, designers dumping on "weak link" Michael C. and one team creating a "horrifying" line, in judge Nina Garcia's terms. It culminated with usually nurturing mentor Tim Gunn delivering a punishing lecture to the designers. With all this drama as a backdrop, the designers try to move on tonight (minus the eliminated A.J.). Here, it's the good, bad and ugly of wedding attire when they must reinvent bridesmaid dresses. — Dean Maurer

10/9c Comedy Central
One of the bonuses of this series' return is that it was able to reach its 100th episode. And in tonight's landmark installment, Fry inadvertently reveals Leela's origins as a mutant who has been living above ground illegally. To make amends, Fry joins the other members of her race, including the band Devo, in an epic clash against the surface people. Tonight also marks the end of its current run, but it will be back in December with a holiday-themed episode featuring the voices of Al Gore and Coolio. — Joe Friedrich

College Football
7:30/6:30c ESPN
Are you ready for some football? The college season kicks off tonight on 18 campuses from Buffalo to Honolulu, with ESPN focusing its cameras on a pair of S.C.'s": Southern Mississippi vs. South Carolina in Columbia and new coach Lane Kiffin's USC Trojans at Hawaii in late-night action. Even under demonstrative head coach Steve Spurrier, South Carolina rarely draws much attention in the crowded SEC, but blue-chip freshman running back Marcus Lattimore could change that as he leads the Gamecocks against an always-tough Southern Miss defense. — Roger Leister

Secrets of Chocolate
8/7c Discovery
Could there be a better time slot tonight for candy-bar companies to pony up some advertising dollars for commercials? The sweet brown stuff that came from cocoa beans gets the spotlight in this documentary examining how chocolate shaped world events, including its role in the Aztec Empire, its service in World War II and how it may help save rain forests. — Michael Chant

Vampire Diaries
8/7c CW
 Isobel and John (Elena's real birth parents) attempt to carry out their devious plan to kill Stefan and Damon in the first-season finale, which first aired in May. Everything comes crashing down as Mystic Falls celebrates its annual Founder's Day event, with Caroline leading the festivities as the reigning queen. And, of course, there is tension between Elena and Bonnie since Bonnie didn't remove the spell from the deadly device that can harm vampires like she promised. This is one festival that is sure to end with lots of fireworks. — Tim Holland