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Guest Star: Brian Thomas Smith

Brian Thomas Smith

Brian Thomas Smith is an American actor best known for his recurring role as Zach Johnson on The Big Bang Theory.

His TV credits include roles on shows including A Good Knight's Quest, Casual: The Series, and The Flip Side. He has had recurring role on TV shows such as The Indies, Wolfpack of Reseda, Suit Up, and The PET Squad Files. His TV credits also include guest appearances on Two and a Half Men and Happy Endings.

You are viewing a list of Brian Thomas Smith's 11 appearances on The Big Bang Theory.

  • The Lunar Excitation

    The Lunar Excitation
    Season 3, Episode 23 - Aired May 24, 2010

    When Leonard goes to invite Penny to come see the guys' experiment on the roof, she is with a new guy, Zack, who she met at the Cheesecake Factory. After Zack asks some dumb questions, even Sheldon claims Penny could do better.

    Appeared as Zack

  • The Alien Parasite Hypothesis

    The Alien Parasite Hypothesis
    Season 4, Episode 10 - Aired December 9, 2010

    When the girls run into Penny's ex, Zack, during a girls' night out, Amy is overcome with new sensations which she struggles to understand. Sheldon helps Amy come to terms with her sexual feelings for Zack, encouraging her to follow her endocrine system.

    Appeared as Zack

  • The Justice League Recombination

    The Justice League Recombination
    Season 4, Episode 11 - Aired December 16, 2010

    After the guys hurt Zack's feelings, they try to make things up to him by taking him to the comic book store. The guys then decide that Zack would be the perfect addition to their Justice League group for the upcoming New Year's Eve costume party.

    Appeared as Zack

  • The Toast Derivation

    The Toast Derivation
    Season 4, Episode 17 - Aired February 24, 2011

    When Sheldon refuses to hang out with his regular group of friends at Raj and Priya's apartment, he forms a new social group including Penny's ex-boyfriend, Zack.

    Appeared as Zack

  • The Thanksgiving Decoupling

    The Thanksgiving Decoupling
    Season 7, Episode 9 - Aired November 21, 2013

    Penny and Leonard's Thanksgiving is thrown into disarray when Penny realizes that her "fake Vegas wedding" to her ex-boyfriend Zack is actually very real. Zack visits the guys as they spend Thanksgiving at Mrs. Wolowitz house so he can sign the annulment papers.

    Appeared as Zack

  • The Cooper Extraction

    The Cooper Extraction
    Season 7, Episode 11 - Aired December 12, 2013

    When Sheldon flies back to Texas for his sister's childbirth, the gang gather to decorate the apartment's Christmas tree. When they begin to wonder what life would be like without Sheldon, they come to realize how big a part of their lifes he has become.

    Appeared as Zack

  • The Fermentation Bifurcation

    The Fermentation Bifurcation
    Season 9, Episode 22 - Aired April 28, 2016

    When the gang run into Penny's old boyfriend Zack, he makes Leonard and Howard worry about the military applications of their guidance system, and causes trouble for Raj's relationships.

    Appeared as Zack

  • The Cognition Regeneration

    The Cognition Regeneration
    Season 10, Episode 22 - Aired April 27, 2017

    When Leonard and Penny run into her ex-boyfriend Zack, who is now happily married, he offers Penny a job.

    Appeared as Zack

  • The Bitcoin Entanglement

    The Bitcoin Entanglement
    Season 11, Episode 9 - Aired November 30, 2017

    When they guys remember mining valuable Bitcoin on a laptop that Leonard gave to Penny, they turn to her ex-boyfriend Zack to try find their digital fortune.

    Appeared as Zack

  • The Propagation Proposition

    The Propagation Proposition
    Season 12, Episode 12 - Aired January 10, 2019

    After Penny runs into Zack at a bar, she and Leonard have dinner on his boat where he asks them for a big favor.

    Appeared as Zack

  • The Donation Oscillation

    The Donation Oscillation
    Season 12, Episode 15 - Aired February 7, 2019

    Zack and Marissa meet Leonard and Penny to discuss their fertility options.

    Appeared as Zack

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