Sarah Chalke and Courteney Cox, Scrubs Sarah Chalke and Courteney Cox, Scrubs

9 pm/ET ABC
The gang from Sacred Heart makes the leap to a new network tonight, kicking off the comedy's eighth season after seven on NBC. Courteney Cox guest stars as Kelso's replacement, who immediately ruffles feathers when she begins making changes around the hospital. J.D., meanwhile, receives a taste of his own medicine as he's frustrated by his new batch of bumbling interns. — Brie Hearn

For clips of Scrubs, visit our Online Video Guide.

10 pm/ET FX
It has been 11 months, so in case you have forgotten, the Sean-Colleen Rose (Sharon Gless) story line turned operatic as they left us last February: She stabbed him while he was operating on Annie. And blood keeps flowing as new episodes (officially, the final eight of last year's strike-shortened season) resume. No spoilers here, but we can say that it's over between Sean and Colleen, and that he won't perform surgery anytime soon. Meanwhile, Christian has health problems of his own. — Paul Droesch

For clips of Nip/Tuck, visit our Online Video Guide.

Biggest Loser: Couples
8 pm/ET NBC
Just three weeks after Michelle Aguilar was crowned the sixth Biggest Loser, the weight-loss juggernaut is back for its seventh season. This time, couples — including grandparents, best friends and former plus-size models — head to the ranch to make serious changes to their waistlines. The group also boasts new record-holders for the youngest, oldest and heaviest contestants. In tonight's episode, the players learn about a new twist to this season's game. — Brie Hearn

For clips of The Biggest Loser, visit our Online Video Guide.

Shatner's Raw Nerve
10 pm/ET Biography
Some things never change. When William Shatner welcomes Leonard Nimoy to the show, he'll once again be in command and firing questions at his old and trusted friend. Of course, in the Star Trek series, there was always some good-hearted ribbing. But, given the nature of Shatner's talk show, how far will he go to push Nimoy's buttons with sensitive subjects? Will the needs of the many (viewers) outweigh the need for privacy of one guest? — Bill Ecklund

For more Leonard Nimoy, visit our Online Video Guide.

8 pm/ET CW
The Wilsons are all about family, but with a new brother in the picture, the family portrait needs to be updated. Too bad Annie's not sold on big brother Sean yet, and after overhearing his suspicious phone call, who knows if she ever will be? Meanwhile, Dixon finds himself the object of yet another girl's attention, and he keeps it from girlfriend, Silver. Tsk-tsk. All these secrets and lies...when will they ever learn? — Rhoda Charles

For clips of 90210, visit our Online Video Guide.