TONIGHT'S MUST-SEE

"ER," 9 p.m., NBC. For eight-plus seasons, Abby Lockhart has brought subtle depth to "ER." First a nurse and now a doctor, she's faced tragedies at work and in her life. Maura Tierney has drawn praise and an Emmy nomination in the role. Some scenes — Abby and Sam discussing visits to abortion offices, for instance — have been quietly powerful. Now comes what's said to be Tierney's final episode. Abby defends Sam (Linda Cardellini) at a hearing and clashes with the new chief (Angela Bassett).

TONIGHT'S MIGHT-SEE

"Eleventh Hour," 9 p.m., CBS. Three 11-year-olds have died of heart attacks, but there are no symptoms of foul play. A scientist (Rufus Sewell) arrives, with a young FBI officer (Marley Shelton) for back-up. On one level, this story does manage to divert and surprise us. On another, it's an upsetting surprise, one that leaves us with a bad feeling. And it adds none of the offbeat wit that redeem similar shows ("House," "The Mentalist").

OF NOTE

"My Name is Earl," 7 p.m., NBC. Earl belatedly feeds his brother's dreams of being a cheerleader. Jenna Elfman plays the "uncheerful" head of the cheerleading camp.

"Kath & Kim," 7:30 p.m., NBC. Kath wants to promote her hair-styling business. She needs her boyfriend to get her a spot in the mall and her daughter to be a model.

"CSI: Crime Scene Investigation," 8 p.m., CBS. A Las Vegas hypnotist is suspected of bank robberies. Who's next? David Copperfield?

"Grey's Anatomy," 8 p.m., ABC. There are ill feelings after Derek finds the diary of Meredith's late mother.

"Saturday Night Live Weekend Update Thursday," 8:31 p.m., NBC. Last week's edition had small flaws — everything was front-loaded, with mostly commercials in the last five minutes — and large laughs. Here's the second of three Thursday shows.

"Life on Mars," 9:01 p.m., ABC. Sam, who remembers being in 2008, reluctantly settles into his work as a cop in 1973. Tonight, he probes shootings at a check-cashing place.