As one of the most successful and longest-running sitcoms in television history, CBS' The Big Bang Theory is able to boast about some pretty impressive things. Recently, it surpassed the iconic sitcom Cheers as the longest running multi-camera sitcom in television history. It has won countless awards and racked up a truly absurd amount of nominations beyond that. Its starring cast have skyrocketed to A-list fame, regardless of whether they were known or unknown prior to the series' premiere.
But it isn't just the main cast of characters that includes some pretty well-known names. Over the course of twelve seasons and nearly 300 episodes, The Big Bang Theory has had an endless parade of A-listers appear in roles of varying significance. Whether science fiction icons, television legends, or real life scientific geniuses, the guest stars on The Big Bang Theory are nothing short of out of this world. We take a look back at the ten best of them all.
10 Bill Nye the Science Guy (Himself)
You'd be hard pressed to find any scientist - whether on television or otherwise - who made a bigger impression on more children than the legend himself, Bill Nye the Science Guy. So it only made sense, really, that Nye would appear in an episode featuring The Big Bang Theory's equivalent of himself - Arthur Jeffries, also known as TV personality Professor Proton.
Bill Nye's appearance on the series is the result of one of Sheldon's many harebrained schemes for getting revenge for what he feels is a wrong that has been done to him. But in the end, rather than make friends with a new television icon, Sheldon only winds up with yet another restraining order from a prominent public figure.
9 Stephen Hawking (Himself)
Many of the guest stars on this list find themselves inadvertently pulled into the world of The Big Bang Theory because of Sheldon's larger-than-life personality and boundless ego. But very few of these characters and their corresponding actors can claim to have found themselves in a war of the minds with Dr. Sheldon Cooper.
The most significant of these so-called rivals was, without question, the legendary genius Stephen Hawking himself. The back and forth barbs exchanged between the scientific geniuses would span multiple seasons, mostly consisting in the form of exchanged voicemails, though Hawking did appear as himself on multiple occasions. Following his passing in 2018, the series also included a touching tribute to the one of a kind genius.
8 Carrie Fisher (Herself)
It wouldn't be a show about real nerds with impressive nerd street cred if they weren't obsessed with Star Wars, Star Trek, or both. The Big Bang Theory gang are, naturally, obsessed with both iconic pieces of science fiction media (among many others) and the series has reflected their very strong opinions by trying to feature as many guest stars from these beloved franchises as possible.
An all too brief, but instantly iconic cameo came in the form of the late Princess Leia herself, Carrie Fisher. Fisher appeared at the very end of an episode which found Sheldon embarking on a crazy adventure with another of Fisher's own Star Wars castmates, James Earl Jones. Jones and Sheldon attempted to ding dong ditch Fisher's home, leading to her running outside armed with a baseball bat.
7 Wil Wheaton (Himself)
Speaking of iconic science fiction stars, Star Trek cast member Wil Wheaton has long recurred on The Big Bang Theory as an over the top version of himself - who becomes Sheldon's seemingly eternal nemesis. Whether they're fighting on dueling bowling teams or warring over who should become television's new Professor Proton, Wil and Sheldon have almost always been at each other's throats.
On a few occasions, it seemed like these two were finally going to be able to let bygones be bygones. But who are we kidding? The rivalry between these polar opposites is one of the best things the series has ever done. Any time Sheldon angrily screams "Wheaton," it's clear things are about to get really good.
6 Laurie Metcalf (Mary Cooper)
It's not just science fiction icons that have popped up on The Big Bang Theory over the years. Longtime television and theatre icon Laurie Metcalf has had a recurring role on the series from almost the very beginning as Sheldon's incredibly religious, conservative, old fashioned mother, Mary Cooper.
Sheldon and his mother are almost always at odds in terms of their beliefs and opinions regarding, well, basically everything. But Mary loves her son more than anything, and she will go to whatever lengths necessary to ensure that he knows this, and that he is happy. Their tender relationship is likewise further explored in the prequel series Young Sheldon, which finds Metcalf's own daughter, Zoe Perry, taking on the role of Mary.
5 Levar Burton (Himself)
While Levar Burton may be best known for his roles as Geordi LaForge in Star Trek: The Next Generation, or Kunta Kinte in Roots, or even as the host of the beloved series Reading Rainbow, LeVar Burton has also made some truly invaluable and hilarious contributions to The Big Bang Theory over the years. None of his guest appearances have been all that long, but every time he appears on the series, something goes horribly - and hilariously - wrong.
On one occasion, he shows up at Sheldon's apartment after a Twitter invite, only to find drunk and half-naked guys singing karaoke. On two other occasions, he appears on Sheldon's Fun with Flags webseries, only to find himself in increasingly uncomfortable situations, due to Sheldon's total obliviousness regarding social protocols. Thankfully, Burton is nothing if not a game comedic performer, and each appearance allows him to make the most amusing facial expressions as a result.
4 Stan Lee (Himself)
Sometimes, when people meet their idols, things go exactly as planned. Other times... that person in question is Sheldon Cooper, and nothing ever goes according to his plan. When Sheldon learned that the father of Marvel himself, Stan Lee, was going to be visiting Stuart's comic book shop, and he would be missing out on it, he was understandably totally beside himself. But Penny, ever a good friend, managed to do some digging and found out where Stan Lee lived, and brought Sheldon for a visit as a surprise.
As if that weren't creepy enough, Sheldon invites himself into Stan Lee's home, and winds up with yet another restraining order to add to his collection. Despite the brief length of the comic book icon's cameo in the series, Stan Lee was, unarguably, one of The Big Bang Theory's biggest gets in terms of star power - and certainly made a lasting impression on Sheldon, and Penny, too.
3 Mark Hamill (Himself)
Mark Hamill may not have been the first member of the Star Wars cast to make a guest appearance on The Big Bang Theory, but he, without question, had the most meaningful appearance, in terms of what he contributed to the series. After Howard meets Hamill while returning a lost dog he found that turned out to be Hamill's, Mark Hamill offered Howard a favor as a show of gratitude for him returning his beloved pet to him.
The favor Howard requested, as we all know, turned out to be that Hamill would consider officiating Sheldon and Amy's wedding. Of course, all along, Wil Wheaton had been readying to do just that, which only furthered the dissension between Sheldon and Wheaton - especially given the Star Wars vs. Star Trek tension. But Hamill turned out to be just the right man for the job, even getting emotionally invested multiple times during the ceremony.
2 James Earl Jones (Himself)
It's often the most fun when a celebrity appears in a guest starring role as a heightened version of themselves - because at that point, there's truly almost nothing that's off limits. In season seven, Darth Vader himself, James Earl Jones, appeared in an episode that feels like nothing short of a fever dream, it's so hysterically hard to believe. After Sheldon runs into James Earl Jones while dining out, the two embark on a bizarre, giddy adventure throughout the city.
Along the way, they visit a carnival, ride a ferris wheel together, pig out on ice cream, sing "The Lion Sleeps Tonight" at a karaoke night, take in a steam bath at a sauna, attempt to prank Carrie Fisher, and more. It's one of the series' most hilarious episodes ever, and none of it would have been possible without James Earl Jones' total commitment to the bit.
1 Bob Newhart (Arthur Jeffries aka Professor Proton)
Few guest stars have contributed more meaningfully to the series overall than the comedy legend Bob Newhart. When Newhart first appeared on the series, he was merely the elderly former children's television show host Professor Proton, or Arthur Jeffries - the man who inspired Sheldon to become a scientist, and now found himself the unlikely object of Sheldon's interrogative devotion during their first meeting.
Over time, however, Newhart's role as Arthur deepened, and became something so very much more meaningful. After Arthur's passing in the series, Newhart would continue to recur as a new version of the character: Force Ghost Arthur, who visits Sheldon in his dreams a la Obi Wan Kenobi, whenever Sheldon is in need of some moral support. No other actor could have made this character, and this recurring gag, so entertaining. Newhart's halting, skeptical, quizzical delivery simply seals the deal each and every time.