Every Celebrity Who Played Themselves On The Big Bang Theory

"The Big Bang Theory," the massively successful sitcom created by Chuck Lorre and Bill Prady that ran for 12 years and the same number of seasons on CBS, celebrated "geek culture" for its entire run and arguably helped bring nerdy interests into the mainstream along with the Marvel Cinematic Universe and major Star Wars projects. The series — which stars Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg, Kunal Nayyar, Mayim Bialik, and Melissa Rauch as Sheldon Cooper, Leonard Hofstadter, Penny, Howard Wolowitz, Raj Koothrappali, Amy Farrah Fowler, and Bernadette Rostenkowski, respectively — welcomed plenty of celebrity guest stars throughout its run, and some, like Christine Baranski and Bob Newhart, played original characters. Others, however, played themselves.

So which celebrities played themselves on "The Big Bang Theory," and how did they fit into the overarching narrative? Here's a list of every single celebrity who appeared in a self-referential cameo on the sitcom (listed in alphabetical order by first name) and how and why they interacted with our lovable gang of dorks.

Leonard Nimoy's voice appears on "The Big Bang Theory" in the Season 5 episode "The Transporter Malfunction," but the Star Trek universe veteran never showed up on the series in person; his son did, though.

In the Season 9 installment "The Spock Resonance," Sheldon, who's trying to work up the nerve to finally propose to Amy, is introduced to Adam Nimoy as the younger Nimoy works on his documentary "For the Love of Spock." (This is a real documentary, by the by.) After revealing that he admired Spock's commitment to logic and lack of emotion as a kid watching various Star Trek projects featuring the elder Nimoy, he tells the man's son that he keeps a napkin used by the Spock actor — gifted to Sheldon by Penny in the Season 2 episode "The Bath Item Gift Hypothesis" — with his most valuable possessions, including a ring intended for Amy.

Adam West, who loved appearing on "The Big Bang Theory," shows up in the Season 9 episode "The Celebration Experimentation" as a surprise guest at Sheldon's surprise birthday party. When he calls Sheldon "Sherman," complains about not getting paid to appear at the party, and compares himself to other Batmans, Sheldon flees into the bathroom to hide.

Tech mogul Bill Gates is name-dropped or mentioned in pop culture all the time — the guy co-founded Microsoft, after all — but he actually deigned to appear in person on "The Big Bang Theory." After Penny leaves her long-held dream of becoming an actor behind and starts working as a pharmaceutical marketing representative, she finds out Gates will be at her workplace one day; her husband Leonard and their friends Howard and Raj are excited, but she tells them she can't get them in to meet the tech entrepreneur. (Sheldon, meanwhile, thinks it's an April Fool's Day prank.)

Unbeknownst to Penny, Leonard, Howard, and Raj figure out where Gates is staying and ambush him, only for Penny to find a way for Leonard to meet Gates later on — which reveals Leonard's deception when Gates recognizes him. As for Sheldon, the guys just keep sending him to wrong hotels to stalk Gates.

Bill Nye, colloquially known as the "Science Guy," actually shows up twice on "The Big Bang Theory." His much bigger role happens in the Season 7 installment "The Proton Displacement," where Sheldon, trying to get the attention of his childhood idol and science-based TV star Dr. Arthur Jeffries, or "Professor Proton" (Bob Newhart), starts hanging out with Nye specifically to make Arthur jealous. In the show's 12th and final season, Nye makes a very small cameo in "The Conjugal Configuration," where he's lightly bullied by Neil DeGrasse Tyson.

In the Season 5 "Big Bang Theory" epsiode titled "The Russian Rocket Reaction" — so named because Howard learns that he's heading to the International Space Station — Wil Wheaton, whom we'll address later, appears alongside another figure from the wider Star Trek universe. This time, it's Brent Spiner, who famously played Data on "Star Trek: The Next Generation," showing up at a party hosted by his co-star Wheaton. When Wheaton gives Sheldon a signed figurine of his character Wesley Crusher, Spiner opens the packaging, infuriating Sheldon; Spiner offers to sign a Data figurine, but the damage is done.

Famous physicist Brian Greene — whose work in areas like string theory and mirror symmetry have proven to be game-changers in the scientific community — briefly appears in the Season 4 episode "The Herb Garden Germination," where Amy and Sheldon attend a talk he hosts at their favorite comic book store.

After Howard goes to space on "The Big Bang Theory," the experience makes him generally insufferable, and even his wife Bernadette is sick and tired of him constantly bringing it up. To try and combat his obsession, Raj shows Howard a clip of real-life astronaut Buzz Aldrin — gamely appearing as himself in a fake YouTube video that's real in the show's universe — boring a bunch of kids trick-or-treating at Halloween with space stories, and Howard sees firsthand how irritating he's being.

The late, great Carrie Fisher — who originated the role of Princess turned General Leia Organa in the Star Wars universe and passed away suddenly in 2016 — briefly showed up on "The Big Bang Theory" in an episode that featured one of her Star Wars cohorts. Fisher, portraying herself, answers the door in a bathrobe and holding a baseball bat after a silly prank conducted by Sheldon and that co-star, whom we'll name in a little while.

When Raj is unexpectedly included on a list of "30 Visionaries Under 30 Years Old to Watch" in People Magazine for discovering the trans-Neptunian space object 2008 NQ₁₇ — which essentially just means a minor planet — he gets a really big head, driving all of his friends crazy. He's really put in his place when he meets Charlie Sheen, the troubled star of Chuck Lorre's other sitcom "Two and a Half Men," at a bar ... and Sheen tells Raj to let him know when he makes the cover.

A "Big Bang Theory" celebrity cameo that didn't age particularly well is Elon Musk, who appeared in the Season 9 episode "The Platonic Permutation." After Bernadette, Raj, and Raj's girlfriend Emily (Laura Spencer) bully Howard into giving back to the less fortunate by volunteering at a soup kitchen for Thanksgiving, he ends up bonding with the Tesla tech mogul, who's also volunteering that day.

TV and radio host Ira Flatow appears in not one, not two, but three episodes of "The Big Bang Theory" as himself. In his first outing on the show in Season 3's "The Vengeance Formulation," we only hear Flatow in a voice cameo. He physically shows up in the Season 7 episode "The Discovery Dissipation" (where he interviews Sheldon and Leonard after Sheldon accidentally discovers a stable super heavy element) and Season 11's "The Retraction Reaction," where he interviews Leonard about his work at the California Institute of Technology and Leonard admits that no major discoveries are being made despite the institution's major budget.

Astrophysicist, Nobel Prize winner, and cosmologist Dr. George Smoot appears twice throughout "The Big Bang Theory." In the Season 2 episode "The Terminator Decoupling," Sheldon, Leonard, Raj, and Howard take a train to San Francisco to watch Smoot deliver the keynote speech at a symposium; afterwards, Sheldon accosts him and suggests they work together and insinuates that he could personally be instrumental in Smoot winning a second Nobel. (Smoot asks if he's on drugs and walks away, and Sheldon, miffed, calls him a "diva.")

This sticks, apparently. In the Season 12 episode "The Laureate Accumulation," Amy and Sheldon look for support after their own Nobel nomination and try to woo Smoot, who simply tosses their gift — a cookie basket — away.

There are a few celebrities in the Season 4 episode "The Hot Troll Deviation," but let's start with George Takei. Takei, who plays Hikaru Sulu in the Star Trek franchise, shows up in Howard's fantasies as he attempts to win Bernadette back after their breakup. Visible only to Howard during ... inopportune moments, Takei provides some dubious dating advice.

TV host Howie Mandel's appearance during Season 6 of "The Big Bang Theory" — specifically, during the episode "The Re-Entry Minimization" — is brief but hilarious as Howard thinks his grand return from space is getting a ton of attention at the airport, only to realize everyone's there for Mandel.

Remember "The Convention Conundrum," the Season 7 episode of "The Big Bang Theory" in which Sheldon pranks Carrie Fisher? His accomplice is James Earl Jones, who voiced Darth Vader in the original Star Wars trilogy — Leia's father and enemy. Why? Well, after Sheldon can't get tickets to San Diego Comic-Con, he decides to throw his own convention; this obviously fails, but he meets Jones in the process, and the two become unexpectedly fast friends. After a night of karaoke, time at a strip club, and plenty of ice cream, Jones and Sheldon prank Fisher and close out their evening with a relaxing visit to a sauna. Even better? Jones then invites Sheldon and the gang to Comic-Con as his guests.

Wil Wheaton, as it turns out in the Season 12 episode "The D&D Vortex," hosts a regular Dungeons & Dragons meet-up ... and it's exclusively attended by celebrities who, in real life, love the tabletop role-playing game. One of them is real, longtime D&D fan and actor Joe Manganiello; according to Variety, Manganiello regularly hosts his own star-studded D&D nights and serves as the DM, or "Dungeon Master," and leads the proceedings.

One of Wil Wheaton's other D&D regulars in "The D&D Vortex" is basketball legend, writer, author, and actor Kareem Abdul-Jabbar, whose resumé includes everything from writing on the 2019 "Veronica Mars" revival to playing with the Los Angeles Lakers. 

Let's return, briefly, to "The Hot Troll Deviation" — because "Battlestar Galactica" star Katee Sackhoff appears in Howard's fantasies in this episode alongside George Takei. Unlike Takei, she's an object of lust for Howard; like Takei, she tries to offer dating advice.

Another big-name celebrity that's part of the Dungeons & Dragons group in "The D&D Vortex" is writer, director, and actor Kevin Smith. Alongside Kareem Abdul-Jabbar, Wil Wheaton, Joe Manganiello, and William Shatner, Smith ends up playing a game with Penny, Bernadette, and Amy ... but we'll return to Shatner later on.

In that Season 12 episode "The Laureate Accumulation," Amy and Sheldon also try to woo Kip Thorne, a 2017 winner of the Nobel Prize in Physics, to support their victory; he, like George Smoot, throws away their gift.

Star Trek and "Reading Rainbow" star LeVar Burton appeared on "The Big Bang Theory" three separate times. In his first appearance in Season 4's "The Toast Derivation," Sheldon is miffed because everybody is skipping their regular Cheesecake Factory visits to not upset Penny with Leonard's new girlfriend, so Sheldon sends a social media post begging Burton to join him at home for dinner. (In the episode's final moments, Burton shows up only to see Sheldon singing to himself in a towel and leaves immediately.)

Burton ultimately returns in the Season 6 installment "The Habitation Configuration" alongside fellow Star Trek veteran Wil Wheaton, who tries and fails to shoot a Trek-themed episode of "Fun with Flags" alongside Amy and Sheldon. When Sheldon replaces Wheaton with Burton, it doesn't help anything (though this time, it's Amy's fault). Burton then makes his final "Big Bang" appearance in Season 8's "The Champagne Reflection," where he returns, yet again, to Sheldon's original creation "Fun with Flags."

One of the very best moments of "The Big Bang Theory" is Sheldon and Amy's wedding in the Season 11 finale "The Bow Tie Asymmetry," which features Luke Skywalker himself Mark Hamill in a key role. After Howard finds Hamill's lost dog — "Bark Hamill" — Hamill owes Howard a favor, and Howard cashes that in almost immediately by asking Hamill to officiate Sheldon and Amy's wedding. (It's also a surprise, as Sheldon is expecting Wil Wheaton to be the officiant.)

Because Sheldon and Amy are late to their own ceremony as they make breakthroughs in their theory of super-asmmetry, Hamill ends up fielding questions from the waiting guests about the Star Wars universe in an attempt to stall. Hilariously, most of the guests know quite a bit more about Star Wars lore than Hamill himself.

Former real-life astronaut Mike Massimino — who, as of this writing, teaches mechanical engineering at Columbia University — appears in a handful of episodes starting in Season 5 of "The Big Bang Theory" thanks to Howard's journey to the International Space Station. As one of Howard's fellow explorers, Massimino joins in and makes fun of Howard, giving him the nickname "Froot Loops" (after Howard's mother is caught yelling about them on a call) in "The Friendship Contraction" before they even go into space. In the Season 5 finale, Massimino listens as Howard recounts his wedding to Bernadette in "The Countdown Reflection," which concludes as the rocket takes off.

Massimino then appears in two episodes of Season 6 — "The Decoupling Fluctuation," where he bullies Howard alongside the other astronauts, and "The Re-Entry Minimization," where they all return to Earth. In Season 7, Massimino asks Howard to return to space (he ultimately says no) in "The Table Polarization," and in Season 8's "The First Pitch Insufficiency," Howard seeks advice from Massimino when Howard is asked to throw out the first pitch for the Los Angeles Angels, and Massimino encourages him not to do it and hits on Bernadette in the process.

Astrophysicist Neil DeGrasse Tyson makes his first "Big Bang Theory" appearance in the Season 4 episode "The Apology Insufficiency," where Sheldon scolds Tyson over the fact that Pluto is no longer considered a planet. (Though Tyson tries to insist that he's not solely responsible, he's rebuffed by a stubborn Sheldon.) Alongside Bill Nye, Tyson reappears during the Season 12 premiere "The Conjugal Configuration" as part of a social media spat.

Influential author Neil Gaiman — whose appearance on "The Big Bang Theory" is now deeply complicated after a 2025 report in Vulture accused him of rampant sexual impropriety — shows up on the sitcom during the Season 11 episode "The Comet Polarization." After Gaiman posts on social media about Stuart Bloom's (Kevin Sussman) comic book store, Sheldon is upset that it's always crowded.

Even though he's the most hopeless romantic in the main cast, Raj is still single at the end of "The Big Bang Theory," but he gets his hopes up at the Nobel ceremony when he sits next to Sarah Michelle Gellar. The "Buffy the Vampire Slayer" star, for her part, is quick to point out that they're not on a date.

Stan Lee, the Marvel Comics co-founder who passed away in 2018, appeared in every Marvel Cinematic Universe project until his death. He also found time to show up in Season 3 of "The Big Bang Theory" — specifically, the episode "The Excelsior Acquisition," which references Lee's catchphrase "Excelsior!" and sees Sheldon and Penny desperately trying to meet Lee after a botched attempt results in Sheldon getting a speeding ticket. Showing up at his house probably wasn't one of their best ideas.

Legendary theoretical physicist Stephen Hawking — who lived for decades and against all odds with a motor neurone disease that ultimately led to him speaking through a computer before his death in 2018 — showed up on "The Big Bang Theory" a whopping seven times, lending his voice to two episodes and physically appearing in five. In Season 6's "The Extract Obliteration," he lends his voice to the show while he plays Words with Friends with Sheldon; in Season 7's "The Relationship Diremption," Sheldon leaves a bunch of stressed out drunken voicemails on Hawking's machine.

As for his on-screen appearances, Hawking first shows up in the aptly named Season 5 episode "The Hawking Excitation," where Howard, tasked with maintaining Hawking's wheelchair, puts Sheldon through a series of embarrassing tests before he'll let Sheldon meet the scientific genius. (He points out an error in Sheldon's work, and Sheldon passes out.) In Season 8's "The Troll Manifestation," it's revealed that Hawking is a troll bullying Sheldon and Leonard's online paper — though he ultimately admits that he liked their paper, but was bored. There's a birthday video call from Hawking in the Season 9 standout "The Celebration Experimentation," and he reappears in Season 10's "The Geology Elevation" on a call with Sheldon where he reveals that even he experiences professional jealousy with his colleagues. Hawking's final appearance is in Season 11's "The Proposal Proposal," where Hawking talks Sheldon through the fact that he'll have to be equals with Amy in their marriage. After Hawking's real-life passing, the Season 11 finale "The Bow Tie Asymmetry" included an ode to him. 

After Sheldon starts panicking about dying in the Season 4 episode "The Cruciferous Vegetable Amplification," he tries to live a healthier lifestyle; when that doesn't work, he creates a robot that can perform everyday tasks while Sheldon remains safely confined to his bedroom. This backfires spectacularly when his friends spot Apple co-founder Steve Wozniak at Penny's job at the Cheesecake Factory — and when Sheldon chats with Wozniak through the robot, Wozniak says he'd sign Sheldon's 1977 Apple II. Naturally, in his haste to run to the restaurant, Sheldon falls down the stairs and breaks the Apple II beyond repair.

Before we see George Smoot in "The Terminator Decoupling" — a standout Season 2 episode of "The Big Bang Theory" — we watch the guys take the Coast Starlight train at Sheldon's insistence. While on board, they spot "Firefly" actress Summer Glau and take turns making her unbelievably uncomfortable. Even though Raj makes some progress, he ends up chickening out when he realizes his beer is non-alcoholic — Raj, in early seasons of the series, can only talk to women if he's drunk — and after Howard talks Glau into taking a picture with him, she breaks his phone.

William Shatner is the final member of Wil Wheaton's tabletop role playing gang in Season 12's "The D&D Vortex," but he appears throughout the episode because Wheaton, trying to be nice, introduces Shatner to Sheldon while Wheaton films as Professor Proton. Sheldon immediately pukes on an irritated Shatner, and when Leonard is secretly invited to join the D&D game, he tells Penny, and Wheaton angrily kicks him out for abusing a friendship with a celebrity. Incredibly, the girls get invited to the game instead.

Wil Wheaton doesn't just make a cameo as himself on "The Big Bang Theory" — he's actually a vital part of the narrative as he plays a hilarious "evil" version of himself. Across 17 episodes, Wheaton, a Star Trek alum, plays Sheldon's nemesis at first; because Sheldon loved Wheaton's character Wesley Crusher, he's held a grudge for decades after Wheaton skipped a signing when Sheldon was just a kid. 

Over time, though, Wheaton and Sheldon become friends, and Wheaton essentially becomes a recurring supporting character, whether he's interfering with Leonard and Penny's relationship during a tense bowling game, inviting everyone over for parties, or helping Penny book an acting role in the truly terrible sequel "Serial Ape-ist 2: Monkey See, Monkey Kill." Still, Wheaton is a delight, and even though he technically plays a different "version" of himself, it's still a thrill to see him portraying this "character" and play with his public image. Wheaton, incidentally, also returns for the spin-off series "Stuart Fails to Save the Universe."

"The Big Bang Theory" is streaming on HBO Max now.