List of The Big Bang Theory Characters - Notable Guest Stars Appearing As Themselves - Cameo Appearances

Cameo Appearances

Charlie Sheen (Season 2, "The Griffin Equivalency"): When Raj discovers a celestial body he is very excited about it. At Penny's restaurant, Raj says to the patron at the next table over, "Hey, buddy. I'm going to be in People magazine!"; Charlie Sheen turns around, takes his sunglasses off and says "Yeah? Call me when you're on the cover." (At the time, Sheen was starring in Two and a Half Men, also produced by Chuck Lorre.)

Analeigh Tipton and Samantha Potter (Season 2, "The Panty Piñata Polarization"): Howard and Raj visit the America's Next Top Model house pretending to be cable television repairmen. Tipton and Potter made appearances, opening the door for Howard and Raj. Tipton greeted Howard and Raj, caught them in a lie as the house does not receive cable television (it receives satellite), but allows them in regardless when Howard "corrects" his error with another lie when he says that they are satellite television repairmen. Potter did not get a speaking role.

George Smoot (Season 2, "The Terminator Decoupling"): After a train ride to a conference in San Francisco, Sheldon presents his paper to 2006 Nobel Prize laureate George Smoot, and proposes joint research; Smoot abruptly rejects his idea by asking "With all due respect, Dr. Cooper, are you on crack?"

Ira Flatow (Season 3, "The Vengeance Formulation"): Sheldon is invited to talk about magnetic monopoles on Flatow's radio show, Science Friday. However, Barry Kripke pulls a prank on Sheldon, and Sheldon is publicly humiliated to a nationwide audience. Flatow's appearance was voice only.

Stan Lee (Season 3, "The Excelsior Acquisition"): When Sheldon has to miss Lee's appearance at the comic book store because he ends up in traffic court after running a red light, Penny tries to make it up to him by taking him to Lee's house, uninvited and unannounced (acquiring Lee's address from Stuart). Lee, not impressed by the unexpected intrusion, sarcastically remarks "why don't you just come in and watch the Lakers game with me?" only for Sheldon, not understanding sarcasm, to rush into the house. Lee, annoyed, decides to sue for a restraining order. When Sheldon announces his "autographed" restraining order to Leonard, Howard, and Raj, he comments it will look great hanging next to his restraining order from Leonard Nimoy.

Steve Wozniak (Season 4, "The Cruciferous Vegetable Amplification") Dines in Penny's restaurant at the same time that the guys are there. He compliments Sheldon for his "virtual presence device" (using Sheldon's name for the device without having heard how Sheldon calls it) and in turn Sheldon (having previously referred to him as "the Great and Powerful Woz") compliments Wozniak telling him that he ranks 15th on his list of favorite technological visionaries. When Wozniak feigns disappointment, Sheldon tries to console him by stating that the ranking is six places ahead of Apple founder Steve Jobs. Sheldon then tells Wozniak that the Apple II was rather "nifty" and is one of his proudest possessions. Wozniak promises Sheldon that he would autograph the computer if Sheldon brought it to him. In the haste to get the Apple II to Wozniak for signing, Sheldon trips and falls down the stairs, breaking the computer.

LeVar Burton (Season 4, "The Toast Derivation" and Season 6, "The Habitation Configuration"): Sheldon invited Burton to a party via a tweet. Upon opening the door and seeing the other guests at the party, Zack, Kripke, and Stuart (who at that moment was wearing nothing but a towel) singing karaoke, Burton leaves and when starting to walk down the apartment block stairs utters that he is "so done with Twitter". He appears again at the end of "The Habitation Configuration", taping an episode of "Fun With Flags" with Sheldon and Amy. Amy says "cut", followed by complaining that "this guy is worse than Wil Wheaton" (referring to Wil's appearance earlier in the episode). Sheldon then tells Burton that because Amy is his girlfriend, he is obligated to agree with her. Burton asks "I still get lunch, right?", to which Sheldon nods. Along with Brent Spiner and Wil Wheaton, Burton makes Star Trek: The Next Generation the most represented franchise on the show in terms of guest appearances.

Brian Greene (Season 4, "The Herb Garden Germination"): Sheldon and Amy attend a book signing event of Greene's popular science book, The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. At the event, Sheldon initially ridicules Greene in private conversations with Amy, but then he gets up and publicly ridicules Greene, asking Greene why doesn't he do something more useful with his time than write popular science (only to turn around and state he was kidding).

Brent Spiner (Season 5, "The Russian Rocket Reaction"): Sheldon shows up at a party thrown by his "mortal enemy", Wil Wheaton, only after he hears that Spiner will be there. After Wheaton gives Sheldon a signed, in-the-box Wesley Crusher action figure, Spiner grabs it and opens it, thus putting him on Sheldon's Mortal Enemies List immediately after Wheaton was removed from the list. Along with LeVar Burton and Wil Wheaton, Spiner makes Star Trek: The Next Generation the most represented franchise on the show in terms of guest appearances.

Howie Mandel (Season 6, "The Re- Entry Minimization"): When Howard returns to earth he hears shouts of "Howie" and believes that the paparazzi is here for him until he learns that they were there for Mandel who had arrived at the airport at the same time as Howard. Mandel thinks Howard is delusional, proclaiming to his driver that during the entire flight, "he kept telling me he's an astronaut."

Buzz Aldrin (Season 6, "The Holographic Excitation"): Raj sends Howard a link showing a video that features Buzz Aldrin handing out candy to kids on Halloween. Aldrin gives space related candy, such as Milky Way, Mars bar, and moonpies. He brags to the kids about his amazing achievement of being an astronaut who walked on the Moon.