The Big Bang Theory Wiki
The Big Bang Theory Wiki

Alex Jensen is a Caltech Physics doctoral student and Sheldon Cooper's assistant. Alex is often required by Sheldon to perform menial tasks, as opposed to assisting with his research. She often uses a very wide-eyed expressisons when having to deal with the gang's unconventional behavior. She displays a strong attraction for the initially oblivious Leonard, much to the chagrin of Penny and with interference from Sheldon.

Character Information


A native of Des Moines, Iowa, she graduated summa cum laude with a concentration in theoretical physics from Stanford University. Inspired by her father, a SETI astronomer, her dissertation concerns looking for Trojan asteroids at Earth's L5 Lagrange point. She gave up an opportunity at Fermilab to come work for Sheldon.


She is introduced in "The Higgs Boson Observation" (S06E03) when Sheldon hires her. Alex happens to be quite skilled with flattery, shown when she uses it to persuade Sheldon to hire her, even though immediately beforehand he insists that flattery does not work on him. When Leonard and Rajesh Koothrappali stop in to visit Sheldon, they meet Alex, whom Rajesh Koothrappali immediately falls for. Later, Alex meets Penny, whom she mistakes for Leonard's assistant. Penny becomes jealous immediately after Alex says how talented he is and she is sure a lot of people want to work with him. Penny says that a lot of people can't and takes Leonard off to the bedroom.

Alex flirting with Leonard.

Alex is next seen in "The 43 Peculiarity" (S06E08), where she tells Rajesh Koothrappali and Howard that not even she knows where Sheldon goes between 2:45 and 3:05 every day and that her corduroy pants are too noisy according to her boss. Later, she shows an obvious interest in Leonard, though Leonard remains oblivious to her flirting and signals of attraction. She compliments him and tells him that girls must hit on him all the time since he is cute and funny, and texts him, saying that she'd like to talk to him again soon. This attention is further explored in "The Egg Salad Equivalency" (S06E12) when Alex suggests that they could discuss the physics lecture she was attending over dinner. Her suggestion really startles Leonard. Although Leonard remains faithful to Penny, her offer does not stop his ego from inflating for the rest of the episode.

Sheldon, however, is jealous that she is showing any form of attention to any physicist besides himself, and attempts to discourage her advances and keep her focused on his needs. His efforts backfire spectacularly when she takes offense to his numerous condescending and demeaning remarks about women and their biological urges, causing her to file a sexual harassment complaint with the Human Resources administrator. The HRA's attempts to show Sheldon that his actions were offensive seem initially successful, with Sheldon later revealing to Alex that he is required to complete an online sexual harassment seminar; however, as he unaffectedly deems his time far too valuable, he asks Alex to take it in his place.

Alex asking Leonard out to dinner.

Alex Jensen next appears in "The Tangible Affection Proof" (S06E16). With Valentine's Day approaching, Sheldon has Alex buy his gift for Amy. Sheldon gives Alex two thousand dollars in various crumpled bills that he finds in his pockets and his desk, and instructs Alex on Amy's interests (monkeys and the color grey) so that Alex can find an appropriate gift for Amy. Alex buys a miniature harp music box that plays Amy's favorite song, a Canterbury Tales' map and a neuron cell drawing drawn and signed by famous neuroscientist Santiago Ramón y Cajal; all items purchased based on Amy's interests. Sheldon likes the drawing so much that he keeps it for himself.



The Big Bang Theory Episodes
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Young Sheldon Episodes
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Appeared M = Mentioned Did not appear Not aired/Not available
V = Voiced C = Cameo F = Flashback I = Indirectly mentioned P = Pictured


  • Alex has made no appearances after Season 6 and no mention of her fate, thus it's unclear what became of Alex after her last appearance, and it's also unknown if she resigned, was fired from being Sheldon's assistant or moved on. 
  • Alex's presence was to force Penny to realize that other smart and pretty women are also interested in her boyfriend Leonard.
  • Alex can be seen as a counterpart to Zack, she was introduced as a love interest for Leonard and elicited jealousy and anger from Penny due to being a better fit for him.
  • Alex's last known appearance in "The Tangible Affection Proof" is the only episode where she doesn't display her crush on Leonard.
  • The last few gang members that Alex still hasn't met are Bernadette, Stuart and Emily since her only appearances in those four Season 6 episodes (1: S6E3, 2: S6E8, 3: S6E12 and 4: S6E16).
  • Her full first name is likely Alexandra, since Alex is short for that name and Alex is a female.
  • She often open her eyes very wide when surprised if shocked by the actions of the guys.


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The Big Bang Theory Characters, Cast & Crew
Characters Main Leonard Hofstadter  ‧  Sheldon Cooper  ‧  Penny  ‧  Howard Wolowitz  ‧  Rajesh Koothrappali  ‧  Amy Farrah Fowler  ‧  Bernadette Rostenkowski-Wolowitz  ‧  Stuart Bloom  ‧  Emily Sweeney (formerly)  ‧  Leslie Winkle (formerly)  ‧  The Social Group
Recurring/Minor Debbie Wolowitz  ‧  Barry Kripke  ‧  Priya Koothrappali  ‧  Dr. V. M. Koothrappali  ‧  Mrs. Koothrappali  ‧  Stephanie Barnett  ‧  Lucy  ‧  Mary Cooper  ‧  Zack Johnson  ‧  Beverly Hofstadter  ‧  Mike Rostenkowski  ‧  Alex Jensen  ‧  Professor Proton  ‧  Missy Cooper  ‧  Ramona Nowitzki  ‧  Dan  ‧  Josh Wolowitz  ‧  Dennis Kim  ‧  Althea Davis  ‧  Jeanie  ‧  Cinnamon  ‧  Mrs. Rostenkowski  ‧  Wyatt  ‧  Claire  ‧  Kurt  ‧  Eric Gablehauser  ‧  Dave Gibbs  ‧  Dimitri  ‧  Alfred Hofstadter   ‧  Meemaw  ‧  Jimmy Speckerman  ‧  Susan  ‧  Randall  ‧  Bert Kibbler  ‧  President Siebert  ‧  Janine Davis  ‧  Colonel Richard Williams  ‧  Halley Wolowitz  ‧  Neil Michael Wolowitz  ‧  Denise  ‧  George Cooper Jr.   ‧  Larry Fowler  ‧  Anu  ‧  George Cooper Sr.  ‧  Marissa
Cast Regulars Johnny Galecki  ‧  Jim Parsons  ‧  Kaley Cuoco  ‧  Simon Helberg  ‧  Kunal Nayyar  ‧  Mayim Bialik  ‧  Melissa Rauch  ‧  Kevin Sussman  ‧  Laura Spencer  ‧  Sara Gilbert  ‧ 
Recurring/Minor Christine Baranski  ‧  Aarti Mann  ‧  John Ross Bowie  ‧  Casey Sander  ‧  Stephen Merchant  ‧  Sara Rue  ‧  Kara Luiz  ‧  Brian Thomas Smith  ‧  Margo Harshman  ‧  Alessandra Torresani  ‧  Matt Bennett  ‧  Keith Carradine  ‧  Laurie Metcalf  ‧  Judd Hirsch  ‧  Carol Ann Susi  ‧  Meagen Fay  ‧  Brian George  ‧  Alice Amter  ‧  Courtney Henggeler  ‧  June Squibb  ‧  Katey Sagal  ‧  Jack McBrayer  ‧  Dean Norris  ‧  Brian Posehn  ‧  Mark Harelik  ‧  Joshua Malina  ‧  Brian Patrick Wade  ‧  Kate Micucci  ‧  Regina King  ‧  Jerry O'Connell
As Selves Wil Wheaton  ‧  Mike Massimino  ‧  Stephen Hawking  ‧  Kip Thorne  ‧ Katee Sackhoff  ‧ Steve Wozniak  ‧ Buzz Aldrin  ‧ Summer Glau  ‧ James Earl Jones  ‧ Carrie Fisher  ‧  Brent Spiner  ‧ Howie Mandel  ‧ Bill Nye  ‧ George Smoot  ‧ George Takei  ‧ LeVar Burton  ‧ Neil deGrasse Tyson  ‧ Brian Greene  ‧ Charlie Sheen  ‧ Stan Lee  ‧ Adam West  ‧  Mark Hamill  ‧ Kevin Smith  ‧  William Shatner  ‧  Joe Manganiello  ‧  Kareem Abdul-Jabbar  ‧  Sarah Michelle Gellar
Crew Writers Chuck Lorre * (Creator)  ‧  Bill Prady * (Creator)  ‧  Steven Molaro *  ‧  Steve Holland *  ‧  Maria Ferrari *  ‧  Jim Reynolds *  ‧  Eric Kaplan *  ‧  Anthony Del Broccolo  ‧  Lee Aronsohn *  ‧  Dave Goetsch *  ‧  Tara Hernandez  ‧  Richard Rosenstock *
Directors Mark Cendrowski  ‧  Peter Chakos * (mainly as Editor)  ‧  Anthony Rich  ‧  James Burrows
Science consultant : David Saltzberg Director of photography : Steven V. Silver
Costume designer : Mary T. Quigley * Unit production manager : Kelly-Anne Lee *
Theme composer / performer : Barenaked Ladies Chuck Lorre Productions
also as Producer The Big Bang Theory : Full cast & crew on IMDb