“The Office” (9 p.m., NBC): On “The Office,” Halloween turns out to be scary

“The Office” (9 p.m., NBC): On “The Office,” Halloween turns out to be scary for Pam when she’s the only one to show up for work in a costume. Meanwhile, corporate headquarters delivers some shocking news.

“30 Rock” (9:31 p.m., NBC): Countless millions have watched Tina Fey’s hilarious impersonations of vice-presidential nominee Sarah Palin, but will they tune in to see her hilarious sitcom? “30 Rock,” which kicks off its third season this week, has garnered critical acclaim and loads of shiny hardware, including two Emmys for best comedy. Still, it has yet to prove it can succeed where it counts the most — in the ratings. Perhaps a guest list featuring Oprah, Jennifer Aniston, Steve Martin and several others, will help. Let’s just hope the big-name visitors don’t throw the show off its game.

“ER” (10 p.m., NBC): The final season of “ER” continues as Dr. Ray Barnett (Shane West), a double amputee, makes a return visit to the hospital that surprises the heck out of Neela (Parminder Nagra), the woman we thought he left behind.