The most successful comedy writers either become their own stars, or find suitable alter egos. And some do both.

In his first two TV hits, “The Office” and “Extras,” Ricky Gervais channeled his peculiar brand of awkwardness into characters David Brent and Andy Millman, respectively. Now in “Life’s Too Short” (9:30 p.m., HBO), Gervais and co-creator Stephen Merchant play themselves and allow the actor Warwick Davis (“Willow”) to utter all of the painful Gervais-like lines.

Davis describes himself as the British movie industry’s “go-to little person.” Or at least he was. This odd comedy (don’t dare call it “small”) centers around his has-been status, his ruined marriage and his increasingly pathetic efforts to either stage a comeback, or discover the next big thing among little people through his talent agency “Dwarves for Hire.” Filled with cruel and obvious sight gags, “Short” begs for the audience to be offended and laugh at its own thin skin.

• Speaking of has-beens clamoring for a comeback, “Celebrity Apprentice” (8 p.m. Sunday, NBC) collects 18 notables whose appropriateness for these shenanigans range from “It figures” to “Has it come to this?”

Only a handful come from the pre-reality TV era, most notably “Star Trek” regular George Takei, ’70s supermodel Cheryl Tiegs and once-promising talk show host Arsenio Hall. Clay Aiken is probably the most surprising choice, furthest from his comfort zone.

• Christmas arrives with drama for Mr. Bates as well as Matthew and Mary on the second season finale of “Downton Abbey” on “Masterpiece Classic” (8 p.m., PBS, check local listings). Fans of these acclaimed British dramas can mark their calendars for the arrival of “Great Expectations” on April 1.

Tonight’s other highlights

• Scheduled on “60 Minutes” (6 p.m., CBS): retraining the unemployed, Norway’s young chess master.

• “The Amazing Race” (7 p.m., CBS) returns for a 20th season.

• Homer and Marge live off the grid and like it on the 500th episode of “The Simpsons” (7 p.m., Fox).

• The stakes get higher on “Luck” (8 p.m., HBO).