By the very nature of 30 Rock, the high-concept NBC comedy was always open to a plethora of celebrity cameos. For one, Tina Fey's Emmy award-winning series was set at the fictional studio for T.G.S. at the real 30 Rockefeller Plaza. This allowed for celebrities to turn up naturally, as it would hardly be implausible that they'd be appearing in-universe for a T.G.S. episode.
For another, though, 30 Rock filmed in New York, as opposed to most other comedies of the era, which filled in Los Angeles. Yes, there are myriad celebrities who turn up for guest spots in L.A., but the New York shooting location allowed for some actors to turn up who might not have otherwise. 30 Rock mostly made excellent use of its guest stars, but it did also occasionally squandered them.
Best: Carrie Fisher
One of the best early episodes of 30 Rock was season two's "Rosemary's Baby," which sees Liz Lemon (Fey) spending the day with her comedy role model, Rosemary Howard (Carrie Fisher).
In the early goings, Fisher was a massive get for the series and this episode really helped put the show on a map of legitimacy. Fisher's role helped demonstrate the show's proclivity for being altogether zany while still satirizing some of the worst of showbiz.
Squandered: Peter Dinklage
Many episodes of 30 Rock featured multiple guest spots per episode. One such example, "Señor Macho Solo," from season three shows that if the cameos are spread too thin, it can lead to them being squandered.
That's what happens when Stewart (Peter Dinklage) has to compete for screen time with Billy Bush, Salma Hayek, Sherri Shepherd, and Jenna (Jane Krakowski) as Janis Joplin. Dinklage would explode into the zeitgeist just two years later, but 30 Rock would've certainly preferred a do-over with his character.
Best: Jim Carrey
A seminal 30 Rock episode from its later seasons, "Leap Day" remains a pinnacle of what 30 Rock can do when there are myriad celebrities turning up. Rather than weave them into the storyline, this episode allows Jim Carrey to exist separately from the myriad narrative thrusts.
Carrey turns up as himself, playing the role of Leap Dave Williams in an all-day USA marathon of the faux comedy, in a send-up of A Christmas Story. It's fiction within the fiction, but it's an expert use of Carrey's presence and prowess.
Squandered: Jerry Seinfeld
Before there was WandaVision, there was "SeinfeldVision," the season two premiere episode of 30 Rock. Jerry Seinfeld plays himself in the episode and while he's pulling off an amusing turn in the installment, it's not quite at the peak of 30 Rock's powers.
Granted, expectations might just be too high. It was the second season of one of the best new comedies in recent memory with a legend of NBC history turning up to have some fun. It just didn't hit the mark of those lofty expectations.
Best: Oprah Winfrey
Most of the time, the presence of Oprah Winfrey in an episode of anything would be profoundly distracting and ultimately an absolute whiff of a cameo (think the somewhat ludicrous turn from Prince in New Girl).
Yet, season three's "Believe in the Stars" actually pulls off the Oprah appearance. She does play herself, albeit a hallucinated version of herself. But this was clearly a seminal episode and the Oprah inclusion was orchestrated to perfection.
Squandered: Paul McCartney
"Live from Studio 6H" is one of the great 30 Rock installments because it's complete nonsense and features stellar cameos (Jimmy Fallon, Donald Glover, Amy Poehler) without any real reason behind them, something only 30 Rock could get away with.
A Beatle even turns up! Paul McCartney was a ton of fun in his brief appearance in the live edition of the east coast episode, but he was squandered because that's where it ended. Yes, McCartney should be free to come and go as he pleases, but one cannot help but be disappointed to see him replaced with Kim Kardashian for the west coast version.
Best: David Schwimmer
Most of the time, great 30 Rock guest spots are defined by how the celebrities played off the series' regulars, like when Devon Banks (Will Arnett) feuds with Jack Donaghy (Alec Baldwin). In the case of Greenzo (David Schwimmer), he could've held up plot arcs all on his own.
Just a few years after Friends concluded, Schwimmer was back on the peacock network in a green backwards hat and a yellow cape. That was the best way to bring back a "Must See TV" legend into the fictional NBC universe.
Squandered: Jennifer Aniston
On the other hand, Schwimmer's Friends counterpart, Jennifer Aniston, was hardly as much fun in her 30 Rock guest spot. Aniston portrayed Claire, the old roommate of Liz and Jenna, but her story in "The One with the Cast of Night Court" felt like an afterthought.
After all, the episode was titled like Friends, but the key part of it was the Night Court aspect. When Tracy (Tracy Morgan) and Kenneth (Jack McBrayer) celebrate the Night Court cast reunion, it's hard to even remember what's going on with Claire.
Best: Matt Damon
Liz dated many men on 30 Rock who were marked by great celebrity appearances, like Floyd (Jason Sudeikis), Drew (Jon Hamm), and Criss (James Marsden). However, it's hard to top Carol Burnett (Matt Damon).
As a sensitive pilot, Matt Damon showed that huge movie stars could still fit in and be obscenely funny on sitcoms. He even turned up for the first live episode in an unforgettable moment. 30 Rock made the most of Matt Damon on the series, even if it was just for four episodes.
Squandered: James Carville
Granted, it's not like expectations were massively high for a guest appearance from James Carville on 30 Rock in the season two episode, "Secrets and Lies." However, Al Gore had appeared as himself three episodes prior and was hilarious. It seemed like political figures could fit into the 30 Rock world.
But the Carville appearance wound up petering out and ultimately feeling squandered. The reference point of "Cajun style" is somewhat forced into the lexicon and Carville ultimately just doesn't fit. They couldn't all be winners, but 30 Rock still had an insanely high batting average with its guest stars.