Stunt casting TV shows is hardly new. "Name" actors have been part of some of the biggest moments in TV history (there's Sammy Davis, Jr. famously kissing Archie Bunker, and Oprah Winfrey's turn as the therapist Ellen comes out to on her '90s sitcom). And aside from contributing their celebrity spotlight to TV milestones, stars rack up ratings. It's arguable that Britney Spears single-handedly saved How I Met Your Mother from cancellation—her 2008 appearance on the series pulled a then-series-high 10.6 million viewers, led to a regular uptick ratings, a renewal at the end of the season, and ultimately a 2009 Emmy nod for Best Comedy Series.
But led by current shows like Glee, 30 Rock, and Entourage, TV seems to be in a sort of guest-star golden age. Recent episodes of these shows featured the likes of Oscar-winner Matt Damon, Michael Phelps, and even Princess Leia, and the list of celebrity cameos (both rumored and confirmed) for next season gets longer by the day. The news that Javier Bardem will appear on an episode of Glee, as a rock star who mentors one of the gleeks, follows previous rumors that everyone from Justin Timberlake to Susan Boyle to Julia Roberts will guest on the show--possibilities that are only borderline outlandish given the recent trend of big-named guest stars.
It's not just the shows that can't get enough star wattage; the celebrities themselves are angling for these short-term TV gigs more fervently than ever before. The benefits of a major guest star for the shows are fairly evident—drumming up press ink and increasing ratings—but now with the A-listers themselves so vested in scoring these spots, maybe it's time to wonder: What's in it for them?