Today on TV

NFL (6:30 p.m., ESPN): Jaguars at Texans

Chuck (7 p.m., Ch. 5): Casey discovers his sensei is a rogue agent.

Terminator: The Sarah Connor Chronicles (7 p.m., Ch. 13): History changes when a terminator is sent back to the wrong time.

Gossip Girl (7 p.m., Ch. 30): It's the Christmas episode — titled It's a Wonderful Lie.

Samantha Who? (8:02 p.m. and 8:31 p.m., Ch. 4): Samantha tries to impress her new boyfriend; Samantha goes on vacation with Andrea and Dena.

Heroes (8 p.m., Ch. 5): In the conclusion of a two-parter, there's a major showdown.

Victor Borge: 100 Years of Music and Laughter (8 p.m., Ch. 7): A tribute to the late Borge, one of the funniest performers ever.

Privileged (8 p.m., Ch. 30): Megan grounds Rose for planning to cheat on her final. (This episode repeats Tuesday at 8 p.m. in the show's regular time slot.)

Boston Legal (9:01 p.m., Ch. 4): Catherine Piper (Betty White) is back.

My Own Worst Enemy (9 p.m., Ch. 5): Edward confronts Alistair.