The Mark Twain Prize” (PBS, 9 p.m.) seems to be less and less about Samuel Clemens and more about who’s available. Hence this year’s 14th annual winner, Will Ferrell, who has the ability to be a very funny fellow, but has just as often been unfunny, or stuck in some terrible movies.

Still, he’s better than, say, Rob Schneider.

So here come a lot of Will Ferrell clips – the cleaner ones, anyway – and a number of tributes from people like Ben Stiller, Molly Shannon, Andy Samberg, Paul Rudd, John C. Reily, Tim Meadows, Jack Black, matthew Broderick, Ed Asner and Billie Joe Armstrong of Green Day.

The whole shebang was recorded last week at the Kennedy Center for the Performing Arts in Washington, D.C., and also featured Conan O’Brien, who brings his “Conan” (TBS, 11 p.m.) to New York for a week’s worth of shows — the first time with his new cable show. No, they won’t let him back into 30 Rock. For one reason, they’ve got something else broadcasting from there tonight, the oddly-named “Rock Center with Brian Williams” (NBC, 10 p.m.), which is not a teen dance party, but a newsmagazine hosted by the evening news anchor, flanked by people from Ted Koppel and Richard Engel to Meredith Vieira and Harry Smith.

“Puss in Boots” isn’t the only “Shrek” spin-off this week. A new special “Scared Shrekless” (ABC, 7:58 p.m.) marks the holiday with the familiar characters, and if the Christmas TV specials are any indication, they’re usually worth tuning in for. It’s one of a veritable candy dish of Halloween offerings tonight.

Halloween means a night-long, six-hour, live investigation by the “Ghost Hunters” (SyFy, 7 p.m.), this year from the Pennhurst State School and Hospital in Pennsylvania. Without editing, they’ll wait around to see if they are visited by anything supernatural, from ectoplasm to the Great Pumpkin.

Katie Holmes appears as the notorious Slutty Pumpkin costume on “How I Met Your Mother” (CBS, 8 p.m.). The holiday infuses lots of other shows too, from “Mike & Molly” (CBS, 9:30 p.m.) to the “Cake Boss” (TLC, 10 p.m.).

They sing a Halloween medley “The Sing Off” (NBC, 8 p.m.) that includes “Ghostbusters” and “Werewolves of London.” “And Robert Englund, the original Freddie Kruger, is guest star on “Hawaii Five-O” (CBS, 8 p.m.).  The first three episodes of “American Horror Story” (FX, 10 p.m.) play toward the witching hour.

Costumes are always a part of “Dancing with the Stars” (ABC, 8:30 p.m.) and tonight’s show will have a tip of the witches hat to the day’s events.

There’s also a raft of scary movies, of course, including the double feature “The Blair Witch Project” (TMC, 8 p.m.) and “Book of Shadows: Blair Witch 2″ (TMC, 9:30 p.m.); “Halloween” (AMC, 8 p.m.) and “Halloween 3” (AMC, 10 p.m.), and capping off a day of horror on Turner Classic Movies, “Village of the Damned” (TCM, 8 p.m.), “Night of the Living Dead” (9:30 p.m.), the documentary overview “Night at the Movies: The Horrors of Stephen King” (11:15 p.m.), “The Innocents” (12:15 a.m.), “The Haunting” (2 a.m.), and “Repulsion” (4 a.m.).

In Monday Night Football (ESPN, 8:30 p.m.), it’s San Diego at Kansas City.

Daytime Talk

Regis and Kelly: Annalynne McCord, Heidi Klum, Nick Lachey. The View: Halloween show. The Talk: Paula Deen, Cloris Leachman. Ellen DeGeneres: Neil Patrick Harris, Bethenny Frankel. Wendy Williams: Mike “the Situation” Sorrentino.

Late Talk

David Letterman: Jesse Eisenberg, Puscifer. Jay Leno: Justin Bieber, David Freese, Lloyd. Jimmy Kimmel: Paul Reubens, Bruno Tonioli, Megadeth. Jimmy Fallon: Heidi Klum, Bill Burr, Lindsey Buckingham, Sheila E. Craig Ferguson: Zooey Deschanel, Neil Gaiman, Amanda Palmer. Tavis Smiley: Robert Borosage, Laura Dern. Carson Daly: Game, Melanie Pullen, Thievery Corporation (rerun). Jon Stewart: Mindy Kaling. Stephen Colbert: Neil MacGregor. Conan O’Brien: Jimmy Fallon, Reggie Watts. Chelsea Handler:Dan Levy, Arden Myrin, Ross Mathews .