The Big Bang Theory Cast (2007–2019)
CBS | Sitcom | 12 Seasons, 279 Episodes | Created by Chuck Lorre & Bill Prady
The Big Bang Theory is an American multi-camera sitcom centered on a group of socially awkward physicists and engineers living in Pasadena, California, whose lives are upended by the arrival of their conventionally charming neighbor Penny. Created by Chuck Lorre and Bill Prady, the show premiered on CBS on September 24, 2007, and ran for 12 seasons until May 16, 2019, accumulating 279 episodes. At its peak, the show was the most-watched scripted television series in the United States, and it spawned the successful prequel series Young Sheldon. Jim Parsons' portrayal of Sheldon Cooper earned four Emmy Awards and became one of the defining sitcom performances of its era.
The Big Bang Theory cast built one of the most profitable ensemble franchises in recent sitcom history. Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg, and Kunal Nayyar formed the show's original quintet, and the chemistry between the five leads was a central reason the series became a CBS ratings juggernaut. The addition of Mayim Bialik as Amy Farrah Fowler and Melissa Rauch as Bernadette Rostenkowski in Season 4 — and their subsequent elevation to series regulars in Season 5 — gave the show more texture and genuine romance, broadening its appeal significantly. By the final seasons, all seven leads were among the highest-paid actors on American television, with the original five reportedly earning over $900,000 per episode.
Main Cast
Jim Parsons
Sheldon Cooper
A theoretical physicist at Caltech with an IQ of 187, an encyclopedic knowledge of science, and a near-complete inability to read social cues — the show's breakout character and Parsons' Emmy-winning signature role.
Johnny Galecki
Leonard Hofstadter
An experimental physicist and Sheldon's roommate whose desire for a normal social life and romantic relationship with Penny drives much of the show's central emotional arc.
Kaley Cuoco
Penny
An aspiring actress from Nebraska who moves across the hall from Sheldon and Leonard; the group's social anchor who eventually marries Leonard and builds a career in pharmaceutical sales.
Simon Helberg
Howard Wolowitz
An MIT-educated aerospace engineer with an overbearing mother, an impressive collection of belt buckles, and the distinction — to Sheldon's constant disdain — of lacking a doctorate degree.
Kunal Nayyar
Raj Koothrappali
An astrophysicist from New Delhi who is initially unable to speak to women unless he has been drinking, a condition that resolves partway through the series as he grows in confidence.
Mayim Bialik
Amy Farrah Fowler
A neurobiologist and Sheldon's eventual girlfriend and wife; her relationship with Sheldon is one of the show's most warmly received ongoing storylines, with both characters winning the Nobel Prize in Physics in the finale.
Melissa Rauch
Bernadette Rostenkowski-Wolowitz
A microbiologist with a high-pitched voice and surprising forcefulness who begins as Penny's coworker, marries Howard, and becomes a successful pharmaceutical researcher and mother.
Supporting & Recurring Cast
| Actor | Character | Role | Seasons |
|---|---|---|---|
| Sara Gilbert | Dr. Leslie Winkle | An experimental physicist and colleague of Leonard's who briefly dates both Leonard and Howard | 1–3, 8 |
| Kevin Sussman | Stuart Bloom | The perpetually unlucky owner of the comic book store where the guys hang out; eventually moves in with Howard's mother | 2–12 |
| Carol Ann Susi | Mrs. Debbie Wolowitz (voice) | Howard's loud, overbearing mother, who is only ever heard off-screen; Susi passed away in 2014 and the character was written out of the series | 1–8 |
| Wil Wheaton | Wil Wheaton | Playing a fictionalized version of himself as Sheldon's nemesis and eventual friend; a recurring fan-favorite throughout the series | 3–12 |
| Laurie Metcalf | Mary Cooper | Sheldon's deeply religious, fiercely loving mother from Texas, whose visits invariably upend the apartment dynamic | 1–12 |
| John Ross Bowie | Barry Kripke | A plasma physicist at Caltech and rival to Sheldon, known for his rhotacism (inability to pronounce the letter "r") | 2–12 |
| Brian Posehn | Bert Kibbler | An affable geologist who becomes a minor recurring figure and, to Sheldon's consternation, wins a MacArthur "Genius" Grant | 7–12 |
| Mark Harelik | Professor Proton (voice, later appearance) | The host of a beloved children's science TV show who becomes a friend to the group; later appears in dream sequences | 6–12 |
| Christine Baranski | Beverly Hofstadter | Leonard's cold, analytically detached psychiatrist mother whose clinical manner contrasts sharply with Mary Cooper's warmth | 2–12 |
| Jerry O'Connell | George Cooper Jr. | Sheldon's older brother, introduced later in the series to expand the Cooper family dynamic | 11–12 |
Creators & Production
Chuck Lorre
Co-creator and executive producer; one of the most prolific sitcom showrunners in television history, also behind Two and a Half Men and Mike & Molly
Bill Prady
Co-creator and executive producer; a television writer whose background in tech and science culture shaped the show's comedic sensibility
Steve Molaro
Writer and executive producer who became showrunner in later seasons and later developed Young Sheldon
Steven Yeun
Production executive at Warner Bros. Television, which co-produced the series alongside Chuck Lorre Productions and CBS Studios
Mark Cendrowski
The show's primary director throughout its run, helming the vast majority of its 279 episodes
CBS Studios
Network and co-production partner; The Big Bang Theory was consistently CBS's highest-rated program for much of its run
About The Big Bang Theory Cast
The casting of The Big Bang Theory involved a famously troubled pilot process. The original unaired pilot featured a different actress in the role that would eventually become Penny, and the character of Bernadette and Amy did not exist in the original conception of the show. CBS ordered a new pilot after the original test audiences responded tepidly, and Kaley Cuoco was brought in to replace the original actress in the neighbor role. The creative decision to not give the character a last name until much later in the series — she is identified on her wedding invitation as simply "Penny Hofstadter" — was an intentional running joke that became a piece of television trivia.
Mayim Bialik brought unusual authenticity to the role of Amy Farrah Fowler: she holds a real PhD in neuroscience from UCLA, making her academic credentials for the character entirely genuine. Her casting was the result of a search for someone who could credibly be presented as a female intellectual counterpart to Sheldon. Bialik's chemistry with Jim Parsons — who became close friends off-screen — produced what many critics consider the show's best long-form relationship arc. Parsons' decision to leave the series after Season 12 was the primary reason the producers chose to end the show at that point rather than continue; the series finale was watched by over 18 million viewers on the night of broadcast.
Frequently Asked Questions
Who stars in The Big Bang Theory?
The Big Bang Theory stars Jim Parsons as Sheldon Cooper, Johnny Galecki as Leonard Hofstadter, Kaley Cuoco as Penny, Simon Helberg as Howard Wolowitz, and Kunal Nayyar as Raj Koothrappali. Mayim Bialik as Amy Farrah Fowler and Melissa Rauch as Bernadette were promoted to series regulars beginning in Season 5.
Who plays Sheldon Cooper in The Big Bang Theory?
Sheldon Cooper is played by Jim Parsons. Parsons won four Emmy Awards for Outstanding Lead Actor in a Comedy Series for the role, as well as a Golden Globe Award, making Sheldon one of the most acclaimed sitcom characters of the 2010s.
How many seasons of The Big Bang Theory are there?
The Big Bang Theory ran for 12 seasons on CBS, from September 24, 2007, to May 16, 2019, producing 279 episodes. The show ended at the peak of its ratings, remaining one of the most-watched scripted series on US television throughout its final years.
Who created The Big Bang Theory?
The Big Bang Theory was created by Chuck Lorre and Bill Prady. Lorre, who also created Two and a Half Men and Mike & Molly, served as an executive producer throughout the run, as did Prady and Steve Molaro, who later became showrunner.
Is there a spin-off of The Big Bang Theory?
Yes. Young Sheldon is a prequel spin-off that premiered on CBS in 2017 and ran for 7 seasons, following a young Sheldon Cooper growing up in East Texas. Iain Armitage played the young Sheldon, with Jim Parsons providing voiceover narration as the adult Sheldon.
How we build these cast lists
For background on how Cast.biz compiles and orders cast credits, see understanding billing order, how TV show casts are built, and our glossary of cast credits.