Khartoum's newfound oil wealth set the stage for conflict with the long-neglected region of Darfur in western Sudan, where rebel groups emerged to claim a share of the country's burgeoning wealth. In response, the Sudanese government armed a proxy militia and unleashed the so-called "Devils on Horseback" on the rebels and civilian farmers in a stampede of brutality. Over the past four years, at least 200,000 people have been killed, 2.5 million driven from their homes, and mass rapes have been used as a weapon of war. Now PBS' Frontline asks why the international community and the United Nations has failed to stop the slaughter, in the documentary On Our Watch. (9 p.m.-10 p.m., MPT, Channels 22/67).
THE BIGGEST LOSER -- 8 p.m.-10 p.m., WBAL, Channel 11 / Contestants must complete a workout challenge that viewers have selected. NBC.
NCIS -- 8 p.m.-9 p.m., WJZ, Channel 13 / The team's search for a trained survivalist wanted in connection with a cold-case murder leads them into the wilderness. CBS.
THE ACADEMY -- 8 p.m.-9 p.m., WUTB, Channel 24 / The class participates in a run through Los Angeles to honor a fallen policeman. MNT.
BONES -- 8 p.m.-9 p.m., WBFF, Channel 45 / Construction workers find a body with its kneecaps surgically removed. Fox.
DANCING WITH THE STARS -- 9 p.m.-10 p.m., WMAR, Channel 2 / Avril Lavigne and Michael Flatley perform as one couple departs. ABC.
THE UNIT -- 9 p.m.-10 p.m., WJZ, Channel 13 / Grey (Michael Irby) gathers information on gang members from his past. CBS.
HOUSE -- 9 p.m.-10 p.m., WBFF, Channel 45 / House (Hugh Laurie) could be out of job after a billionaire entrepreneur (Chi McBride) takes control of the hospital. Fox.
BEFORE THE FLOOD -- 9 p.m.-11 p.m., Sundance / Rising sea levels threaten Tuvalu, an island nation in the Pacific Ocean.
NIP/TUCK -- 10 p.m.-11 p.m., FX / Unfortunate events unfold for unlucky Dawn Budge (Rosie O'Donnell).
THE REAL HOUSEWIVES OF ORANGE COUNTY -- 10 p.m.-11 p.m., Bravo / McKenzie, Lindsey, Megan and Ashley head to Miami's South Beach.
FRANK TV -- 11 p.m.-10 p.m., Sundance / Comedian and impressionist Frank Caliendo puts a new face on late-night television with this sketch-comedy show.
THE TYRA BANKS SHOW -- Banks and six other women undergo physical transformations for a social experiment about inner beauty. (11 a.m., WUTB-24)
THE VIEW -- Actors Blake Lively and Penn Badgley; guest co-host Trisha Yearwood performs. (11 a.m., WMAR-2)
OPRAH WINFREY -- Winfrey reveals the list of her favorite things from 2007. (4 p.m., WBAL-11)
From Web, wire reports
Critic's Pick--Snoopy and the rest of Peanuts gang gather for an unusual feast in A Charlie Brown Thanksgiving (8 p.m., WMAR, Channel 2).