Over its 12-season run, The Big Bang Theory wasn’t just known for its geeky humor and lovable oddballs—it also became a magnet for some truly memorable guest stars.
The show brought in everyone from Hollywood legends to actual Nobel-winning scientists, blending sitcom laughs with unexpected cameos that kept audiences guessing.
Here’s a look back at 18 guest stars you might not remember, but who each left their mark on TV’s favorite group of brainy misfits.
1. Stephen Hawking
Famous for: Being one of the most renowned theoretical physicists of all time
Episodes: “The Hawking Excitation” (Season 5), “The Extract Obliteration” (Season 6), “The Relationship Diremption” (Season 7), “The Troll Manifestation” (Season 8), “The Celebration Experimentation” (Season 9), “The Geology Elevation” (Season 10), “The Proposal Proposal” (Season 11)
Stephen Hawking, the brilliant mind behind groundbreaking theories on black holes and relativity, made a whopping seven appearances on the show. In his first appearance, Sheldon Cooper nearly faints when meeting his idol, who points out an error in Cooper’s paper.
2. James Earl Jones
Famous for: Voicing Darth Vader in Star Wars and Mufasa in The Lion King
Episode: “The Convention Conundrum” (Season 7)
When Sheldon decides to host his own comic convention, he seeks out James Earl Jones to be a guest. However, their night out takes an unexpected turn, proving to be quite different from what Sheldon had imagined.
3. Carrie Fisher
Famous for: Playing Princess Leia in the Star Wars franchise
Episode: “The Convention Conundrum” (Season 7)
In a surprising twist, Carrie Fisher and James Earl Jones, both Star Wars legends, had never met prior to their appearance on The Big Bang Theory. In the episode, Sheldon and James Earl Jones get caught playing Ding Dong Ditch at Fisher’s house.
4. Bill Nye
Famous for: Hosting the educational science show Bill Nye the Science Guy
Episodes: “The Proton Displacement” (Season 7), “The Conjugal Configuration” (Season 12)
Bill Nye, a science educator and television personality, appears in two episodes of the series. In one instance, Sheldon attempts to make Professor Proton jealous by inviting Nye to his apartment, which ultimately leads to Nye being added to the list of celebrities with a restraining order against Cooper.
5. LeVar Burton
Famous for: Hosting Reading Rainbow and playing Geordi La Forge in Star Trek: The Next Generation
Episodes: “The Toast Derivation” (Season 4), “The Habitation Configuration” (Season 6), “The Champagne Reflection” (Season 8)
LeVar Burton appears as a fictionalized version of himself in three episodes. In two of those appearances, he guest stars on Sheldon and Amy’s web series, “Fun with Flags”.
6. Wil Wheaton
Famous for: Playing Wesley Crusher in Star Trek: The Next Generation
Episodes: Recurring role throughout the series
Wil Wheaton initially appears as a rival to Sheldon, but over the course of the series, their relationship evolves into a friendship. Wheaton’s recurring role makes him one of the most memorable guest stars on the show.
7. Leonard Nimoy
Famous for: Playing Spock in the original Star Trek series
Episode: “The Transporter Malfunction” (Season 5)
While Leonard Nimoy never physically appeared on the show, he did lend his voice to an episode in which Sheldon has a dream featuring a Spock action figure. Nimoy’s cameo was a delightful surprise for Star Trek fans.
8. George Takei
Famous for: Playing Hikaru Sulu in the original Star Trek series
Episodes: “The Hot Troll Deviation” (Season 4), “The Thanksgiving Decoupling” (Season 7)
George Takei, another Star Trek legend, appears in two episodes of the series. In one episode, he and Howard engage in a humorous back-and-forth about Howard’s mother.
9. Katee Sackhoff
Famous for: Playing Kara “Starbuck” Thrace in Battlestar Galactica
Episode: “The Vengeance Formulation” (Season 3)
Katee Sackhoff, known for her role in the sci-fi series Battlestar Galactica, appears as herself in an episode where she flirts with Howard in his daydream.
10. Summer Glau
Famous for: Playing River Tam in Firefly and Cameron in Terminator: The Sarah Connor Chronicles
Episode: “The Terminator Decoupling” (Season 2)
Summer Glau, a fan-favorite actress in the sci-fi community, guest stars as herself on a train ride where the guys are trying to win over Raj’s attention.
11. Brent Spiner
Famous for: Playing Data in Star Trek: The Next Generation
Episode: “The Russian Rocket Reaction” (Season 5)
Brent Spiner, best known for his role as the android Data in Star Trek: The Next Generation, appears as himself at a comic book store, where he gets into a heated argument with Sheldon.
12. Adam West
Famous for: Playing Batman in the 1960s Batman TV series
Episode: “The Celebration Experimentation” (Season 9)
Adam West, the iconic actor who portrayed Batman in the 1960s TV series, makes a cameo appearance at Sheldon’s birthday party.
13. Charlie Sheen
Famous for: Starring in Two and a Half Men and numerous films
Episode: “The Griffin Equivalency” (Season 2)
Charlie Sheen, known for his role in the sitcom Two and a Half Men, appears as himself at an awards show attended by Raj and Penny.
14. Buzz Aldrin
Famous for: Being the second person to walk on the moon
Episode: “The Holographic Excitation” (Season 6)
Buzz Aldrin, the legendary astronaut who was part of the historic Apollo 11 mission, makes a cameo appearance as himself, meeting the gang at Howard’s costume party.
15. Elon Musk
Famous for: Being the CEO of SpaceX and Tesla
Episode: “The Platonic Permutation” (Season 9)
Elon Musk, the visionary entrepreneur behind SpaceX and Tesla, appears as himself in an episode where he volunteers at a soup kitchen with Howard and Raj.
16. Steve Wozniak
Famous for: Co-founding Apple Inc. with Steve Jobs
Episode: “The Cruciferous Vegetable Amplification” (Season 4)
Steve Wozniak, the co-founder of Apple, makes a guest appearance as himself, having dinner with the gang and discussing his work in the early days of Apple.
17. Stan Lee
Famous for: Creating numerous iconic Marvel Comics characters
Episode: “The Excelsior Acquisition” (Season 3)
Stan Lee, the legendary comic book writer and creator of many beloved Marvel characters, appears as himself in an episode where Sheldon attempts to get his autograph.
18. Neil deGrasse Tyson
Famous for: Being a renowned astrophysicist and science communicator
Episode: “The Conjugal Configuration” (Season 12)
Neil deGrasse Tyson, a popular astrophysicist and host of the series Cosmos, makes a guest appearance as himself, officiating Sheldon and Amy’s wedding.
Read Next:
Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
