Guest Star: 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
Season 3, Episode 23 - Aired May 24, 2010When 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
Season 4, Episode 10 - Aired December 9, 2010When 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
Season 4, Episode 11 - Aired December 16, 2010After 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
Season 4, Episode 17 - Aired February 24, 2011When 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
Season 7, Episode 9 - Aired November 21, 2013Penny 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
Season 7, Episode 11 - Aired December 12, 2013When 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 lives he has become.
Appeared as Zack
The Fermentation Bifurcation
Season 9, Episode 22 - Aired April 28, 2016When 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
Season 10, Episode 22 - Aired April 27, 2017When 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
Season 11, Episode 9 - Aired November 30, 2017When 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
Season 12, Episode 12 - Aired January 10, 2019After 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
Season 12, Episode 15 - Aired February 7, 2019Zack and Marissa meet Leonard and Penny to discuss their fertility options.
Appeared as Zack