The Big Bang Theory main characters
Leonard Leakey Hofstadter (portrayed by Johnny Galecki; seasons 1–12) is an experimental physicist with an IQ of 173. Originally from New Jersey, he received his PhD at age 24, spending at least some of his time at Princeton University. He shared an apartment in Pasadena with colleague and friend Dr. Sheldon Cooper for much of the series. Unlike his equally geeky friends, Leonard is interested and adept in building relationships with other people. Compared to his friends, he is relatively successful with women. Leonard comes from an accomplished family. His mother, Dr. Beverly Hofstadter, is a neuroscientist and world-renowned psychiatrist with whom he has a strained relationship. His sister is a medical researcher, his father, Dr. Alfred Hofstadter, is an anthropologist, and his brother Michael is a Harvard law professor. He and Penny date on and off throughout the series, eventually marrying and finding out that Penny is pregnant in the series finale.
Leonard makes a brief non-speaking cameo as a child in the Season 2 finale of Young Sheldon; he was portrayed by Isaac Harger as a child.
Sheldon Lee Cooper (portrayed by Jim Parsons; The Big Bang Theory seasons 1–12, Young Sheldon season 7; voiced by Parsons; narrator: Young Sheldon; and by Iain Armitage; guest: The Big Bang Theory season 12; main: Young Sheldon) is a theoretical physicist, possessing a B.S, M.S, M.A, Ph.D, Sc.D, I.Q. of 187, and eidetic memory. Born in East Texas, he was a child prodigy and received his PhD at age 16 from the California Institute of Technology. He is a cold, condescending, self-centered, and immature person but is rarely malicious. He is obsessed with routines and any disruptions distress him enormously. He shows signs of obsessive–compulsive personality disorder, often shown through his compulsive need to knock three times on a door while saying the name of the person behind the door three times too and the superiority complex. Despite his narcissism, selfishness, and lack of social graces, he does care about his friends and family. In seasons 1–9, he shares an apartment in Pasadena with friend and fellow physicist Dr. Leonard Hofstadter. From then after, he moves in with his girlfriend and eventual wife, Amy. It is revealed in Young Sheldon that they have kids too.
His interest in science fiction and comic books borders on the extreme. He has a particular affinity for Spock from the Star Trek franchise. Although he has the tendency to take things literally, he is fond of occasionally telling a joke or playing a prank, which he typically punctuates with his trademark exclamation, "Bazinga!"
As portrayed in Young Sheldon, he is a child prodigy who finishes primary school before his twin sister, Missy, and joins the same high-school class as his older brother, Georgie, at the age of nine. He reads widely and possesses an eidetic memory. He prefers to learn topics that interest him on his own—such as Faraday's law of induction and gravitational lensing—than the standard curriculum of grade school. In this series, the origins of his interests in the sciences, engineering, computers, trains, comic books, and science fiction (especially the character Spock from Star Trek) are revealed. Sheldon moves on to college while Missy remains in middle school. Despite their rivalry, Sheldon and Missy are closer than they first appear.
Iain Armitage, who plays young Sheldon on the spin-off, briefly appears in a video tape being watched by Parsons during a final season episode of The Big Bang Theory; it is the only time Parsons and Armitage have appeared together so far.
Kindhearted and outgoing, Penny (portrayed by Kaley Cuoco, main: The Big Bang Theory seasons 1–12; guest: Stuart Fails to Save the Universe season 1) is Leonard and Sheldon's neighbor across the hallway from the inception of the series, replacing the apartment's former occupant, Louis/Louise, a "transvestite with a skin condition" according to Sheldon. Originally from a small town outside Omaha, Nebraska, she was a waitress and occasional bartender at the local Cheesecake Factory until season seven, and is an aspiring actress. Sheldon describes her as a "good-natured simpleton" and is critical of her dropping out of community college.
Initially, not much is known about Penny's family, but it is mentioned in the series that her father, Wyatt (portrayed by Keith Carradine,) raised her like a boy, her mother Susan smoked marijuana while she was pregnant with her, her sister shot her husband while they were intoxicated, and her brother Randall is a meth dealer. Susan (Katey Sagal) and Randall (Jack McBrayer) are finally seen in the first episode of season ten. Her last name is never revealed during the series; though it is hinted at in an episode of season two, she ultimately adopts the last name Hofstadter after marrying Leonard. Leonard and Penny date on and off throughout the series which is a big plot point of the show, they eventually marry and find out she's pregnant in the series finale.
Penny makes a brief non-speaking cameo as a child in the Season 2 finale of Young Sheldon, she was portrayed by Quinn Aune as a child. Cuoco additionally voices the pool water, part of one of young Sheldon's nightmares, in the spinoff.
Howard Joel Wolowitz, M.Eng. (portrayed by Simon Helberg; main: the Big Bang Theory seasons 1–12; guest: Young Sheldon season 5) is an aerospace engineer at Caltech's Department of Applied Physics who often hangs out at Leonard and Sheldon's apartment. Unlike Sheldon, Leonard, and Raj, Howard does not have a doctorate and often gets disparaged as a result, especially by Sheldon. He defends this by pointing out that he has a master's degree in engineering from MIT and that the equipment he designs is launched into space, unlike the theoretical work of his friends. In the fifth-season finale, Howard goes to the International Space Station on Expedition 31.
Howard lives in Altadena with his domineering, belittling, and unseen mother, who treats him like a child. While he sometimes expresses irritation at this treatment, for the most part, he appears to prefer it. Howard and his mother often communicate with each other from different rooms by yelling, a habit which Bernadette also adopts in later episodes. Howard fancies himself a ladies' man and attempts pick-up lines whenever a woman is present, although he drops this habit once he starts going out with Bernadette. He is a non-observant Jew. Over the course of the series, he and Bernadette marry and have two children.
In the pilot episode, he speaks English, French, Mandarin, Russian, Arabic, and Persian, along with constructed languages like Klingon and Sindarin. Howard has asthma, transient idiopathic arrhythmia, allergies to peanuts, almonds, and walnuts, and is prone to canker sores and pink eye.
Howard makes a brief non-speaking appearance in the Season 2 finale of Young Sheldon, in which he was portrayed by Ethan Stern as a child; he returns to reprise himself in a narration with Helberg's voiceover for a Season 5 episode.
Rajesh Ramayan Koothrappali, PhD (portrayed by Kunal Nayyar, main: The Big Bang Theory seasons 1–12; recurring: Stuart Fails to Save the Universe season 1) is Howard Wolowitz's best friend. Often called "Raj" by his friends, he is from New Delhi, India, and works in the physics department at Caltech, researching astroparticle physics. Raj comes from a very wealthy family in India, and often communicates with his parents, Dr. and Mrs. Koothrappali, via webcam. He did at least part of his higher education at the University of Cambridge and like most of the scientists bar Wolowitz, Raj also has a PhD. He has a younger sister, Priya. He lives in an apartment in Pasadena. As with his friends, he is mutually involved with and obsessed with science fiction and comic books in general. He is also a fan of Harry Potter and Indian music, but appreciates the Indian lullabies his mother sang and the catchiness of Hindi phrases. Unlike his male friends, Raj has many feminine interests, such as reading Archie comics and Twilight and watching chick flicks such as Bridget Jones's Diary. It is speculated that Raj might be gay due to his feminine interests and his close friendship with Howard, with whom he has arguments similar to those of a married couple. However, Raj has always stated that he is straight, but metrosexual. He was infatuated with Penny, and secretly wrote love poems about Bernadette.
Raj is a Hindu and believes in karma (reincarnation), but eats beef. He is very shy around women outside of his family, and during the first six seasons of the show, found himself unable to speak to women while in their presence unless he drank alcoholic beverages, or believed he had done so. He eventually is able to get over this condition and starts to, unsuccessfully and for short periods, date women.
Raj makes a brief non-speaking cameo as a child in the Season 2 finale of Young Sheldon, he was portrayed by Rishabh Prabhat as a child.
Leslie Winkle, PhD (portrayed by Sara Gilbert; main: season 2; recurring: season 1; guest: seasons 3 and 9) is an experimental physicist who shares her lab with Leonard. In appearance, she is essentially Leonard's female counterpart, equipped with black-framed glasses and sweat jackets. She has lazy eye. She is one of Sheldon's archenemies due to their conflicting scientific ideas and takes every opportunity to insult Sheldon for mistreating her.
However, she and Sheldon are later shown to be more friendly and her antagonism becomes increasingly less malicious and more playful.
The character is based on Gilda, a coworker to Leonard and Sheldon envisioned by creators Chuck Lorre and Bill Prady in the unaired original pilot.
Bernadette Maryann Rostenkowski-Wolowitz, PhD (portrayed by Melissa Rauch; main: The Big Bang Theory seasons 4–12; recurring: The Big Bang Theory season 3, Stuart Fails to Save the Universe season 1) is originally a waitress and co-worker of Penny's at The Cheesecake Factory, using her wages to pay for her graduate studies in microbiology. She is a smart, short-tempered, ruthless, competitive young woman. Despite her short stature and squeaky voice, she is regarded as being intimidating, largely because of her sharp tongue, aggressive demeanor and tendency to be a bully. A recurring joke in the series references Bernadette and her lab team handling dangerous or infectious specimens, leading to accidental byproducts.
Bernadette's approach to business and science is often shown to be somewhat unethical, which she acknowledges often in a cheerful or nonchalant way.
While initially not getting along with Howard's mother, she eventually becomes like her, domineering and passive aggressive, even adopting her signature yell.
Bernadette has a strong maternal personality on many occasions, and is one of the few characters who can easily control Sheldon, and frequently shows him more empathy than others might.
She and Howard have two children, Halley and Neil Michael (whom they call Michael), in seasons 10 and 11 respectively.
Bernadette is of Polish origin and Catholic upbringing, and was originally seen wearing a cross necklace.
Bernadette makes a brief non-speaking cameo as a child in the Season 2 finale of Young Sheldon, she was portrayed by A. J. Coggeshall as a child.
Amy Farrah Fowler, PhD (portrayed by Mayim Bialik; main The Big Bang Theory: seasons 4–12; guest: The Big Bang Theory season 3, Young Sheldon season 4 and 7, Stuart Fails to Save the Universe season 1) is a neuroscientist with a research focus on addiction in primates and invertebrates, occasionally mentioning such experiments involving addiction. (Bialik herself has a PhD in neuroscience.) She is Sheldon's love interest in the series, and they marry at the end of season 11. They are revealed to have children in Young Sheldon.
Early on, Amy is essentially a female counterpart to Sheldon; as the series progresses, she begins a campaign to increase Sheldon's feelings for her by becoming more involved in his interests, including video games and Star Trek, and treating him as his mother did.
In 2020, a year after The Big Bang Theory went off the air, it was revealed that Kate Micucci, who ultimately got the role of Lucy, had auditioned for the role of Amy Farrah Fowler.
Amy makes two appearances in Young Sheldon. She makes an appearance as a child in the Season 2 finale where she is portrayed in a non-speaking role by Lily Sanfelippo. Bialik returns to play Amy in the narration of the season 4 premiere, and in a physical appearance in the series finale.
Stuart David Bloom (portrayed by Kevin Sussman; main: The Big Bang Theory seasons 6 and 8–12, Stuart Fails to Save the Universe; recurring: The Big Bang Theory seasons 2–5 and 7) runs the Comic Center in Pasadena, the comic book store that the characters often visit. Stuart is characterized by his low self-esteem and loneliness, which often result in pathetic attempts to engage with women and win favor with the gang. This is despite owning his own business and being a talented portraiture artist who attended the Rhode Island School of Design.
One of the running gags on the show is Stuart's medical situation. It is depicted as disastrous, so much so that he can be seen under various medical treatments. He is said to have depression and possible malnutrition, among other problems.
In the last season, Stuart's life seems to be turning around. His comic store becomes successful and he gets a steady, long-term relationship.
Kevin Sussman was a recurring guest actor from seasons two to five, and was promoted to starring role for the sixth season onwards.
Stuart is the main protagonist of his own spin-off series Stuart Fails to Save the Universe.
Emily Sweeney, M.D., (portrayed by Laura Spencer; main: season 9; recurring: seasons 7–8; guest: season 10) is a dermatology resident at Huntington Hospital, whom Raj finds on an online dating site. Raj enlists Amy's help to be his "online wingman" and talk to Emily in his behalf. Amy tells Emily about this and it puts her off. Amy and Emily end up hitting it off, having both gone to Harvard and both being into quilting. While Amy and Emily are at lunch together, Raj crashes the lunch. This drives Emily away from both Raj and Amy this time. Later, Raj and Emily meet again, accidentally and hit it off. They eventually double date with Howard and Bernadette, which horrifies Howard. He and Emily had a horrible date, which ended because Howard had gas station sushi, got food poisoning and clogged and overflowed her toilet. Emily is not afraid to stand up for herself or to others when necessary. She is shown to have a slightly alarming personality trait: she delights in the macabre.
Raj ends up breaking up with her before Valentine's Day so he could be with Claire (Alessandra Olivia Toreson). Unfortunately for Raj, Claire had just gotten back together with her boyfriend. So, he eventually lost them both. Emily attempted to get back into Raj's good graces and did manage to sleep with him one last time, but it didn't last.
Laura Spencer was a recurring guest actress on the series in seasons seven and eight. During production of season 9, she was promoted to a "fractional" starring role; the upgraded status ensured her availability on an as-needed basis, without requiring her in every episode. She returned as a guest in season 10.
