TONIGHT: We've got Mariah Carey's holiday special, Merry Christmas to You, plus new episodes of Tabatha's Salon Takeover, The Sing-off, How I Met Your Mother, Rules of Engagement, Two and a Half Men, The Closer, and much more!

8:00 PM

How I Met Your Mother Lily and Marshall receive shocking news that prompts the gang to reflect on their own lives; Robin gets a new job; and Ted begins carrying out tasks as Punchy's Best Man. Alex Trebek has a cameo. (CBS)
The Sing-off The groups perform rock songs and guilty pleasures, and collaborate to sing Green Day's "21 Guns." (NBC)

8:30 PM

Rules of Engagement Russell takes Adam's idea for holiday gift-giving, surprising everyone in the office; and Audrey is determined to make people laugh at Jeff's holiday party. (CBS)

9:00 PM

Mariah Carey: Merry Christmas to You Mariah Carey performs songs from her second holiday album, "Merry Christmas II You," including "Oh Santa!" Taped at the Orpheum Theatre in Los Angeles. (ABC)
Two and a Half Men Charlie and Courtney split up, and a depressed Charlie seeks solace from his psychiatrist, Dr. Freeman. (CBS)
The Closer Chief of Police Tommy Delk (Courtney B. Vance) enlists the team to investigate thefts at various medical-marijuana dispensaries. The seemingly innocuous assignment takes a perilous turn, however, when one robbery results in murder. Before long, the case even tests Brenda's readiness to rise to a higher departmental post. (TNT)

9:30 PM

Mike & Molly Mike and Molly spend their first Christmas together, and Mike has no idea about what to give her. (CBS)

10:00 PM

Hawaii Five-0 Chin Ho is abducted and an explosive device is strapped to his chest. The abductor is Victor Hesse, who murdered McGarrett's fathe (CBS)
Tabatha's Salon Takeover Tabatha springs into action to save a California salon owned by an elitist couple holding college degrees and corporate backgrounds—-but no real-world salon experience. The pair also disrespect their hairdressers, driving the staff away. Tabatha works to show the couple the ropes while giving newfound confidence to their frustrated employees. (Bravo)

Who's on the Late Night Couches Tonight?

Conan:Gwyneth Paltrow, T.J. Miller, Jimmy Eat World (TBS)
The Daily Show: Gordon Brown (Comedy Central)
The Colbert Report: Patti Smith (Comedy Central)
Jimmy Kimmel Live!: Rachael Ray, Garrett Hedlund, Darker My Love (ABC)
The Tonight Show with Jay Leno: Mark Wahlberg, Olivia Wilde, Good Charlotte (NBC)
Lopez Tonight: Eric Stonestreet, J.B. Smoove, Dov Davidoff (TBS)
Chelsea Lately: Nicki Minaj, Jo Koy, Loni Love, Dr. Drew Pinsky (E!)
Late Night with Jimmy Fallon: Jessica Alba, Colin Quinn, Stephen Bishop (NBC)
Late Show with David Letterman: Ricky Gervais, Hailee Steinfeld, Diddy-Dirty Money, a Top Ten List presented by Heisman Trophy winner Cam Newton (CBS)
Late Late Show with Craig Ferguson: Tom Arnold, Alison Becker, Erica Hill, Chris Wragge, Jeff Glor, Marysol Castro (CBS)