As the character David St. Hubbins observes in “This Is Spinal Tap”: “It’s such a fine line between stupid and clever.” Both ends of that spectrum are on display in the parody series “Garth Marenghi’s Darkplace” (9 p.m., Sci Fi). The series consists of an elaborate put-on, presenting itself as a look back at a quickly canceled British horror show from the 1980s.

The action takes place at the haunted Darkplace Hospital, where doctors and staff contend with ridiculous horror cliches like a portal to hell, a psychic cat and psychokinetic colleague who make “Carrie” look like an amateur. The hair, clothes, title sequence and sets are purposefully ludicrous and serve only to punctuate the insane violence, dreadful dialogue and hammy and admittedly amateur-level acting.

“Darkplace” is accompanied by wraparound documentary footage of the “actors” and Marenghi (Matthew Holness) himself looking back at their “craft.” Marenghi takes credit for writing, directing, producing, editing and acting in every episode. Marenghi credits his prolific output to his rare status as an author who “has written more books than he’s read.”

Brazenly silly, “Darkplace” is more forced and over the top than “Spinal Tap” and “Austin Powers” but should appeal to fans of both.

¢ Marvel maestro Stan Lee is host to “Who Wants to Be a Superhero?” (8 p.m., Sci Fi), a comic-book variation on the reality elimination series. Thousands of would-be heroes submitted themselves, their costumes and stories to Lee, who in turn chose 12 to appear on this series.

The contestants dwell together in a secret lair, and they submit to challenges and get eliminated at a rate of two per hour over six episodes. Although the participants, including Monkey Woman, The Creature, Major Victory, Fat Momma and Ty Veculous, take the contest very seriously, “Superhero” unfolds with an appropriate air of whimsy. Lee appears as a Wizard of Oz-like figure on flat-screen TV sets and even billboards to offer encouragement and rebuke to players who uphold or transgress the comic-book code.

Superhero fans should enjoy this and appreciate the fact that the show celebrates the passions of the comic-book community while saving its satirical barbs for the tired conventions of the reality-TV genre.

Tonight’s other highlights

¢ Julie Chen is host to “Big Brother All-Stars” (7 p.m., CBS).

¢ A broken water heater puts a damper on Christmas on “Everybody Hates Chris” (7 p.m., UPN).

¢ Earl regrets tasteless comments on “My Name Is Earl” (7 p.m., NBC).

¢ Hidden talents emerge on “Master of Champions” (7 p.m., ABC).

¢ The results are read on “So You Think You Can Dance” (8 p.m., Fox).

¢ Regis Philbin hosts “America’s Got Talent” (8 p.m., NBC).

¢ A Hollywood heartthrob expires under delicate circumstances on “CSI” (8 p.m., CBS).

¢ Meredith loses focus while worrying about her mother on “Grey’s Anatomy” (8 p.m., ABC).

¢ A rookie learns the ropes on “Without a Trace” (9 p.m., CBS).

¢ Celebrations and secrets on “Windfall” (9 p.m., NBC, TV-14).