And after nine seasons, most thought American Idol had sung its last note once Simon Cowell quit judging the singing competition. But Fox soldiered on with the show, embarking on an Office-esque search for a bold-faced replacement, coming up with two: Jennifer Lopez and Steven Tyler. It's remarkable, critics were quick to point out, how refreshing the two musicians were on the judging panel--a surprising combination that worked. Audiences tuned in to see their chemistry. But as the season wore on, their spark dimmed, audiences ditched, and bloggers queued up their "How to Save Idol" posts, once again.

And what of Spader? His brief appearance on the Office finale was uncharacteristically dark for the show, basing his character, Robert California, on an aggressive and, as Meghan Carlson at Buddy TV writes, "slightly terrifying sexual energy." That particular vibe could certainly be mined for interesting character conflict and relationships early on in Spader's stint. Promo clips of Spader's character at his most overconfident, most outlandishly intense, will certainly entice an audience to watch initially. But how can that character trait stay fresh before overpowering the endearing, awkward, and slightly precious mood emanated by the rest of the Office cast? Worse, it sounds like such an extreme character would easily cross to the wrong side of the line that Steve Carell always precariously toed: too grating. The novelty, I predict, will wear off.

That's not to say that famous actors and TV are always a disastrous combination. Series that have been conceived and premiered on the strength of big Hollywood names have thrived. Showtime, in particular, has made a name for itself wooing "movie actors" to the small screen with rousing success on Californication (David Duchovny) and The Big C (Laura Linney), for example. But those stars were part of the series from the beginning. The success and longevity of those shows is tethered to those actors, just as The Office's was to Steve Carell. And anyone who watched Gwyneth Paltrow shimmy onto Glee and completely reinvigorate the series can speak to the power of an A-list guest star. But as a mid-series run replacement? The trick just doesn't work.

Series that have been successful after replacing its famous lead have done so with lesser-known stars. When Kirstie Alley subbed for Shelley Long on Cheers, she was best known only for a small role in Star Trek. ER never went after a name to succeed George Clooney, relying instead on seasoned, not-so recognizable performers like Goran Visnjic and Maura Tierney to carry the series. Same for Law and Order and its 20-year cycle of detectives.

So will James Spader really save The Office? Of course, that remains to seen. But we'll actually have two chances this fall to see if a series can be salvaged by a famous replacement. Two and a Half Men will premiere with Ashton Kutcher as the central character, stepping in for a scandal-ridden Charlie Sheen (things come full circle). Undoubtedly, Men will premiere to dynamite ratings. The show was already the number one comedy on TV, and public interest in the Sheen debacle is high. Curiosity and Kutcher's polar-opposite-to-Sheen demeanor will spike the series' success initially. But if history tells us anything, Men, like The Office won't be "winning" in the long run.

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