TONIGHT'S MUST-SEES

"Cat Dancers," 6 p.m., HBO. A deep sense of pain and pleasure ripples through this documentary. Ron and Joy Holiday met as dance-class kids. He went away to New York, returned a year later and found she'd transformed into a peroxide blonde with a bikini body. They starred in stage shows and (in Ron's case) muscle magazines. They expanded their act, adding tigers and leopards; they also added a second man stirring rumors, eventually true, of a three-way sexual affair. Their world flowed with artistry, elegance and animal magnetism. Then the tragedies cascaded; by the end of this film, most of the people and animals have been killed. At 75 minutes, this is a very interesting documentary; at 45, it would have been much better.

"Big Bang Theory," 7 p.m., CBS. One of TV's best comedies offers its Christmas episode, with some twists. Leonard befriends a guy at work — who lusts for Penny, Leonard's dream-girl-next door. Meanwhile, Sheldon feels he has to get a Christmas gift for Penny. This isn't easy, for a guy who knows very little about women ... or, for that matter, any people.

OF NOTE

"Terminator: The Sarah Connor Chronicles," 7 p.m., Fox. This wraps up the first half of the season, with the second half starting next month. Tonight, Riley gets closer to John, then faces Cameron; meanwhile, Sarah finds a blogger who seems to know a lot.

"Chuck," 7 p.m., NBC. This isn't the way Christmas Eve is supposed to go: An inept crook ends up at the Buy More, taking Chuck hostage, along with his sister and her fiance. The other spies want to simply remove Chuck, to keep his identity secret; however, he doesn't want to abandon the others.

"I Want a Dog For Christmas, Charlie Brown," 7 p.m., ABC. Think of this 2003 cartoon as a preview for the real one; "A Charlie Brown Christmas" reruns Tuesday.

"Heroes," 8 p.m., NBC. There are fierce conflicts on all sides. It's Nathan against his brother Peter, with huge aftershocks. Meanwhile, friends try to rescue Hiro and Sylar has hostages at Primatech.

"20/20: Drama High: The Making of a High School Musical," 8-10 p.m., ABC. This documentary follows the development of "The Wiz" at a Virginia high school.

"My Own Worst Enemy," 9 p.m., NBC. This double-identity stuff gets complicated: Edmund finds a dangerous way he can switch back and forth with Henry; Tom meets someone who knew him as Raymond.