What’s On Tonight: Gandalf And Colbert Discuss Hobbits, Meaning Of Life, More Hobbits

Adventure Time (Cartoon Network, 7:30 p.m.) — I’m hijacking the Adventure Time listing, not because you shouldn’t watch Adventure Time, because you should watch Adventure Time, but because Sir Ian McKellen (not pictured above) is on The Colbert Report tonight for “Hobbit Week.” They’ll discuss his Pet Shop Boys past.

How I Met Your Mother (CBS, 8 p.m.) — Ted looks after Baby Marvin for Marshall and Lily, so expect multiple variations on the word “manny” from Barney. “More like child care brovider,” he probably says at some point.

2 Broke Girls (CBS, 9 p.m.) — Abby Elliott wins this month’s “Poor Rachel Dratch Award” for the most depressing former-SNL cast member guest appearance: she plays an intern on tonight’s 2 Broke Girls. Don’t worry, Abby, I’m sure Siobhan Fallon Hogan will reclaim the trophy for an unrivaled 24th time soon enough.

Blake Shelton’s Not-So-Family Christmas (NBC, 10 p.m.) — This sketch and singing special features an appearance from Jay Leno. It’s not a lie to say that I would kill all of your families before watching Blake and Jay croon “Silver and Gold.” Shoulda been you, DMX.

Castle (AMC, 10 p.m.) — “Beckett and Castle work on a Christmas list together.” Is it Hanukkah yet?

LATE NIGHT GUESTS: John Krasinski and Led Zeppelin on Letterman; Gerard Butler and Olivia Munn on Leno; Seth MacFarlane, Miranda Kerr, and Richie Sambora on Ferguson; Keira Knightley and Dave Matthews Band on Fallon; Chris Tucker on Conan; Denis Leary on Stewart; and Ian McKellen on Colbert.

Always relevant.