Proof that ordinary people will do just about anything to show up on television can be found on “Mad Mad House” (7 p.m., Sci Fi). This latest variation on “The Real World” is set in a mansion where the five hosts represent five decidedly “alternative” lifestyles.

Don claims to be a vampire. Fiona is a self-proclaimed Wiccan witch. Iya Ta’Shia is a practicing Voodoo priestess. Art calls himself a “modern primitive.” Being primitive appears to involve poking yourself with as many spikes as possible and covering your body in tattoos. Good news: The “primitive” lifestyle does not preclude wearing sunglasses and sunning yourself in the tattooed buff by the pool. Finally, meet Avocado, the “naturalist.” He eats only raw food, walks around naked quite frequently, and mixes the most delicious smoothies.

Their guests have absolutely no clue about what awaits them. In typical “reality” fashion, they’re a mix of exhibitionists, including a self-proclaimed Republican virgin who lives in a convent; a “retired” stripper; a writer who makes his living as a janitor in a barber shop; a handsome guy who “wishes everyone was Christian”; a self-described “player”; two former beauty queens; a frat boy; and a horse trainer who claims to be smarter than he sounds.

Each week, the freaky five will vote off one contestant. Those who fail to conform to their new surroundings and their hosts’ proclivities will get the boot.

“Princess Diana: The Secret Tapes” (9 p.m., NBC) features never-before-seen film clips and audio interviews with the late Princess of Wales, who died in 1997. A second segment will air next week.

While I have no idea why folks will tune in to hear a 12-year-old interview with a woman who has been dead for six-and a half years, I know this marks a new decline in the fortunes of NBC’s “Must-See-TV” lineup. First “The Apprentice” replaces two sitcoms, and now “ER” takes a two-week sabbatical to be replaced by material that seems better suited to “Dateline.” And you wonder why network audience share continues to decline.

Tonight’s other highlights

• Susan flips out on “Survivor: All Stars” (7 p.m., CBS).
• Ben Stiller and Owen Wilson are hosts of an evening of “Starsky and Hutch” repeats (TV Land), beginning at 7 p.m.
• Another player hears The Donald say, “You’re fired!” on “The Apprentice” (8 p.m., NBC).
• A partially deaf woman receives a digital hearing device on “Extreme Makeover” (8 p.m., ABC).
• Scheduled on “PrimeTime” (9 p.m., ABC): a Texas woman discusses her kidnapping and rape ordeal; a woman who rescues teens from a polygamous cult.

Late night

Viggo Mortensen and Sting appear on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno welcomes Mya on “The Tonight Show” (10:35 p.m., NBC).

Michael Imperioli and Tom Jones chat on “Late Night with Conan O’Brien” (11:35 a.m., NBC) … Tricia Helfer is booked on “The Late, Late Show with Craig Kilborn” (11:37 a.m., CBS).