Without “Idol” to boost ratings, it’s all about the guest stars tonight on Fox. Gwyneth Paltrow returns to “Glee” (7 p.m., Fox) as Holly Holliday, the less-than-secure substitute teacher. In this episode, Holly takes over the sex-education class and joins Mr. Schuester in imparting some new ways of looking at the birds and the bees. Look for John Stamos in a guest stint as well.

Fresh from her appearance at the Oscars, Paltrow has gone from being a widely admired actress for movies like “Shakespeare in Love” to a poster child for the kind of celebrity many fans love to hate. Some resent her thinness or ability to wear designer clothes. Others recoil at her making public pronouncements on American culture while living with a rich rock star in the United Kingdom. And others find her attempts to do all that while passing as a Nashville country singer just a bit too much.

The folks at “Glee” must know what they’re doing. Some tune in to enjoy Paltrow’s obvious talents. Others just want to see her fail. That’s a win-win situation, I guess.

Elsewhere on Fox, Mary Lynn Rajskub guest stars on “Raising Hope” (8 p.m., Fox). Best known for her long turn as Chloe on “24,” comic actress Rajskub has made a career out of playing socially awkward characters. She was seen recently on “Modern Family” as Mitchell’s embittered one-time girlfriend.

On “Hope,” she appears as the new wife of Mike (Skyler Stone), the dysfunctional family’s cousin just back from a six-month spiritual quest. In a comedic spoof of “Big Love” and TLC’s “Sister Wives,” Mike has taken a wife as well as three “brother-husbands” (Paul F. Tompkins, Kent Avenido and Christopher Frontiero). And if that weren’t guest stars enough, look for J.K. Simmons (“Law & Order”) as Mike’s estranged father.

• Speaking of strange TLC series, “Tiniest Tween: Kenadie’s Story” (9 p.m., TLC) invades the privacy — er, I mean celebrates the specialness — of what the network describes as “7-year old Kenadie’s extraordinary life as a primordial dwarf.”

Grammar school can be tough for anyone, but imagine being just 33 inches tall and tipping the scales at 17 pounds. The early onset of puberty is one of the side effects of her singular condition. So I guess that’s where the “‘tween” comes in.

Tonight’s other highlights

• Catch five hours of “Bizarre Foods” with Andrew Zimmern” (5 p.m. through 10 p.m., Travel).

• Jim must act without being detected on “No Ordinary Family” (7 p.m., ABC).

• Anna prepares to power up the new reactor on “V” (8 p.m., ABC).

• Joan bails out of babysitting duties for a comic gig on “Joan and Melissa: Joan Knows Best?” (8 p.m., WE).

• A serviceman’s murder trial tests Alicia and Cary on “The Good Wife” (9 p.m., CBS).

• Adam stands up for Max, perhaps too forcefully, on “Parenthood” (9 p.m., NBC).