Johnny Galecki as Leonard Hofstadter-Then
Johnny Galecki has been playing Leonard Hofstadter since day one, when audiences were introduced to the experimental physicist sharing an apartment with the eccentric Sheldon Cooper. He quickly became lovestruck by their new neighbor, the beautiful Penny.
Johnny Galecki as Leonard Hofstadter-Now
Johnny may have been known to audiences since the early 90s when he was on Roseanne, but with his role on The Big Bang Theory, he was introduced to a new crowd. His performance has earned him several award nominations, including one for a Primetime Emmy for Outstanding Lead Actor in a Comedy Series. Since 2014, he has been earning $900,000 for each episode of future seasons he films, which he downgraded from $1 million per episode so Mayim Bialik and Melissa Rauch could receive equal pay.
Jim Parsons as Sheldon Cooper – Then
Sheldon has been charming audiences with his bumbling social mishaps since the very first episode of The Big Bang Theory. He works alongside Leonard at CalTech as a theoretical physicist, an occupation he often finds superior to Leonard’s experimentation. Jim Parsons perfectly captures Sheldon’s misguided sense of superiority that earned him a Ph.d at an exceptionally early age, but fails to recognize the nuance of social situations. Despite his lack of social mores, his friends continue to stick by his side.
Jim Parsons as Sheldon Cooper – Now
It can be hard to believe sometimes that Sheldon proved to be Parson’s big break, given his facile performance on the show. He has gone on to win a number of prestigious awards for playing Sheldon, including four Primetime Emmy Awards for Outstanding Lead Actor in a Comedy Series and one Golden Globe. Parsons made his Broadway debut in 2011 in A Normal Heart, and has parlayed his popularity into a salary of $900,000 per episode alongside his costars.
Sara Gilbert as Leslie Winkle – Then
Sara Gilbert is another actress who got her start on Roseanne that went on to appear on The Big Bang Theory. Playing Leslie Winkle, essentially the female version of Leonard, the two got to re-live their onscreen relationship when Leonard asks Leslie out in Season 1, fearing that a girl like Penny would never go out with him. Leslie, however, often clashed with Sheldon, making the relationship difficult to maintain. Leslie would eventually go on to have a dalliance with Howard as well.
Sara Gilbert as Leslie Winkle – Now
Though it has been several years since Sara has appeared on The Big Bang Theory, she is still most often recognized for her years playing Darlene Connor on Roseanne, a role she has agreed to reprise in the upcoming revival that is set to be released in 2018. Sara will also be serving as an executive producer on the new production. Sara is also the co-host of CBS’s The Talk and is married to wife Linda Perry, with whom she is raising three children.
Mayim Bialik as Amy Farrah Fowler – Then
Mayin joined the cast of The Big Bang Theory at the end of season 3 as Amy when the guys conspired to set up a dating profile for Sheldon. Her sometimes tenuous grasp on social situations made her a good foil for Sheldon, as they had relationship experiences and expectations that were more on par with one another. Amy is neurobiologist, a degree that actress Mayaim Bialik actually holds in real life. The show has developed Amy and Sheldon’s relationship slowly throughout the seasons.
Mayim Bialik as Amy Farrah Fowler – Now
Mayim has been acting since she was 12 years old, and prior to The Big Bang Theory was best known as Blossom, from the TV show with the same name. Mayim is the only cast member to hold a Ph.D in real life as well as on the show, where she gets to bring her scientific expertise into her role. She is also very vocal about her religious Jewish observance as well as her veganism.
Simon Helberg as Howard Wolowitz – Then
Though often looked down upon by Sheldon because he ‘only’ holds a Master’s degree in engineering from MIT, Howard eventually manages to parlay his expertise into becoming an astronaut for NASA. In the early seasons, Howard was often trying and failing to score a date with a variety of different women, That all changed with Penny introduces him to her coworker Bernadette in season 3, who was working at the Cheesecake Factory in order to pay for grad school.
Simon Helberg as Howard Wolowitz – Now
Simon is another one of the original cast who has been with The Big Bang Theory since day one, when he was introduced as the nerdy mama’s boy, still caught under his overbearing mother’s thumb. Recently, Simon has also managed to fit in several film appearances in addition to his work on The Big Bang Theory, including a turn as the pianist Cosme McMoon in Florence Foster Jenkins, which also starred Meryl Streep and Hugh Grant.
Laura Spencer as Emily Sweeney – Then
Laura Spencer plays the slightly morbid dermatologist that Raj meets via online dating during the seventh season of the show. She becomes entangled in a love triangle with Raj and another woman he’s dating, Lucy, but Emily is unfazed. The two enjoy watching horror movies together, and she entertains Raj with macabre jokes. They eventually enter into a fairly serious relationship, but Raj finds in the end that he is still struggling with commitment.
Laura Spencer as Emily Sweeney – Now
Raj wasn’t the only one two timing, as Laura Spencer was also appearing in Bones as Jessica Warren, which recently wrapped production. While it’s unclear whether or not Laura will reprise her role as Emily in the near future, as Raj recently broke up with her again, she doesn’t seem to have ruled out the possibility. In the meantime, Laura recently filmed a short film called Vitality, where she plays the role of Christine.
Kunal Nayyar as Rajesh Koothrappali – Then
Raj is the final piece of the original geek squad who has been with the show since the very start. Raj is an astrophysicist from New Delhi, who is closest to Howard. During the early seasons of the show, Raj had such severe social anxiety that he would be unable to speak whenever a woman was in the vicinity, a problem he discovered would diminish when he was drunk. Eventually, he managed to recover from his crippling anxiety.
Kunal Nayyar as Rajesh Koothrappali – Now
Like his fellow costars, Kunal is best known for his work on The Big Bang Theory. As his character Raj has progressed, Kunal has had more exciting storylines to portray on the show. Along with Simon Helberg, he is now commanding a salary of $750,000 per episode for the current season. In addition to his work on The Big Bang Theory, Kunal was recently in the movie, Dr. Cabbie, where he played Tony. He has also done some voiceover work as Guy Diamond in Trolls.
Kevin Sussman as Stuart Bloom – Then
Kevin Sussman was introduced to the show as Stuart during the second season, as the owner of comic book store that the guys frequent in Pasadena. Though he isn’t one of the core members of the group, Stuart often pops up during their misadventures, though the character struggles even more than they do to fit in. Stuart is characterized by his often depressed demeanor that is usually the result of some mishap or another.
Kevin Sussman as Stuart Bloom – Now
Kevin has been working for a long time prior to starting The Big Bang Theory. His prior roles included appearances on Ugly Betty, as well as working on the film A.I. Artificial Intelligence, which Steven Spielberg directed in 2001. Kevin’s real life isn’t exactly similar to the struggling existence he portrays at Stuart. In addition to his regular work on The Big Bang Theory, Sussman reprised his role as Steve in the Netflix series, Wet Hot American Summer: First Day of Camp in 2015.
Carol Ann Susi as Debbie Wolowitz – Then
We may have never known what Howard Wolowitz’s mother Debbie actually looked like, but the descriptions the characters gave throughout the seasons only made her off screen comments more hilarious. Characterized as the quintessential Jewish mother, who must have been born and raised in the heart of New York City, she showed her love for her son by smothering him. Howard was so dependent on his mother that he even lived in her house until his marriage to Bernadette.
Carol Ann Susi as Debbie Wolowitz – Now
Sadly, Carol Ann Susi passed away from lung cancer in 2014 at 62. Though she always remained off screen, Debbie Wolowitz was a beloved and integral character to The Big Bang Theory throughout the years. The show memorialized her by having the character pass away as well, which allowed the actors to pour their very real grief into their work. Following her death, the producers wrote on the vanity card, Mrs. Wolowitz, every time you spoke, we laughed. You’re in our hearts forever.”
Aarti Mann as Priya Koothrappali – Then
Raj’s younger sister, Priya, who is studying law was introduced to the gang beginning in the fourth season. She and Leonard developed a romance that they tried to keep hidden from Raj, though he eventually discovered them. Priya unfortunately was still jealous of Penny and told Leonard that he didn’t to cut her out of his life. In the end, it didn’t matter as Raj and Priya’s parents made her move back to India when they found out about the relationship.
Aarti Mann as Priya Koothrappali – Now
Since her appearances on The Big Bang Theory, she has been working consistently on various TV shows. Some of her roles include Maria Monrow on Suits, as well as appearing as Agent Laura Kenney in an episode of Scandal. Lately, she has made an appearance on Grey’s Anatomy as Holly Harner, and has just finished shooting to films. One, called Sharon 1.2.3. is due out later this year, the other, Love Sonia is scheduled for release next year.
Sara Rue as Stephanie Barnett – Then
When Stephanie was introduced, she was yet another woman Howard was trying to make a move on. A sassy surgical resident at Fremont Memorial Hospital, she has no interest in Howard, but sets her sights on Leonard instead. Though Howard was initially upset, Leonard and Stephanie proceed to get into a serious relationship, until Leonard realizes that she has essentially moved into his room little bit little. Leonard ends the relationship by dumping her over text message.
Sara Rue as Stephanie Barnett – Now
Sara hasn’t appeared on The Big Bang Theory since she and Leonard broke up in 2008, but she has been working consistently on television ever since. She spent three years playing Brenda on Rules of Engagement between 2010 and 2013, followed by a run on Mom as Candace. From 2015 to 2017, Sara played Karen Delfs on Bones, which just wrapped recently. Next year, she will appear in a number of episodes of the Netflix show, A Series of Unfortunate Events as the Librarian.
Margo Harshman as Alex Jensen – Then
The character of Alex is introduced as a doctoral student placed with Sheldon as a research assistant, but Sheldon often gave her busy work, rather than actually allowing her to help him. When he brings her back to the gang with him, she develops a noticeable crush on Leonard, which Penny takes note of, though Leonard remained oblivious. She eventually tries to ask Leonard out, but he maintains his fidelity to Penny and turns her down.
Margo Harshman as Alex Jensen – Now
Prior to her run on The Big Bang Theory, Margo Harshman was a regular on the Disney Channel show, Even Stevens, when she played Louis Stevens’s friend, Tawny Dean. Margo has been working consistently since she finished her arc on The Big Bang Theory. Her most notable role since then has been Delilah Fielding on NCIS, a run which began in 2013 that is ongoing as of this year. This year she also appeared in Love on the Vines as Diana Armstrong.
John Ross Bowie as Barry Kripke – Then
Barry Kripke established himself from the get go as one of Sheldon’s many nemeses from his first introduction in season two. Aside from constantly antagonizing the gang as a rival physicist, though one who studies plasma and string theory, Barry is still beloved for his sarcastic quips that are always punctuated by his speech impediment that prevents him from properly pronouncing his r’s. John Ross Bowie has made appearances as Barry in every season since his introduction.
John Ross Bowie – Now
John Ross Bowie has had an extensive career on screen from long before he began working on The Big Bang Theory. Bowie has been working in comedy for years, as both a performer and as a writer, prior to moving into film acting. Bowie has continued to participate in a number of other acting projects in the time he’s not filming The Big Bang Theory. Most recently, he has began starring as the father in Speechless, Jimmy DiMeo.
Wil Wheaton as Wil Wheaton – Then
As the child star of Star Trek, Wil Wheaton was the perfect actor to play an exaggerated version of himself on The Big Bang Theory. His entrance as a celebrity Sheldon had been dying to meet was played perfectly when he turned out to be less than kind, disappointing Sheldon so much that he became yet another of Sheldon’s enemies, for a time at least. Though the two have seemed to set aside their differences now, it’s not always easy being Sheldon’s friend.
Wil Wheaton – Now
Richard William Wheaton III, better known as Wil Wheaton began acting as a child when he was cast in Stand by Me. He followed up the role with a long run as Wesley Crusher on Star Trek: The Next Generation. Wil has been acting consistently since his start, and he also often works as a voice over artist. In addition to his current work on The Big Bang Theory, he also hosts his own YouTube series, titled TableTop.
Laurie Metcalf as Mary Cooper – Then
As written on the show, Mary Cooper, played by another Roseanne alumna, Laurie Metcalf, Mary is almost the antithesis of her genius son Sheldon. Mary is an extremely religious Christian, whose beliefs often directly contrast with Sheldon’s. Even so, she’s a caring mother, always showing up to help Sheldon when he’s most in need, usually when alerted by a concerned Leonard. Metcalf has been playing Mrs. Cooper since the character’s introduction.
Laurie Metcalf – Now
Laurie Metcalf has had a prolific career over the years, ever since her role as Roseanne’s sister Jackie on the sitcom, Roseanne. She has also appeared on a number of other shows including Desperate Housewives, Getting On, and more recently, the short-lived The McCarthy’s. She has also voiced Andy’s mom in all three of the Toy Story movies, in addition to several other film roles. Most recently, Laurie won a Tony award this past spring for her work on Broadway.
Christine Baranski as Dr. Beverly Hofstadter – Then
The inimitable Christine Baranski has been appearing on The Big Bang Theory since 2009 when she was cast as Leonard’s psychiatrist mother, Dr. Beverly Hofstadter. Leonard and his mother don’t exactly have a close relationship, as Beverly often considers Leonard a psychiatric experiment before she sees him as a son. He was often humiliated by her use of him as a parenting experiment, and has been constantly working for her approval his entire life.
Christine Baranski – Now
If you’re as consistently impressed by Christine’s stellar performances as the icy Beverly, it might be because she trained at the exclusive Juilliard School in New York City. Though she excels as the steely psychiatrist on The Big Bang Theory, Baranski has an incredible amount of range as an actress, both on the stage and on film. She has appeared in several musicals, including the film adaptations of Chicago and Mama Mia!. She recently wrapped The Good Wife, and will be seen in its spin off.
Brian George as Dr. V.M Koothrappali – Then
Brian George has been playing Raj’s hilarious father, Dr. V.M. Koothrappali since the beginning when he appeared in season one. Given that Raj’s parents are still living and working in New Delhi, they are often seen only over video chat, and usually together. We finally get to meet the senior Dr. Koothrappali, who is a well regarded gynecologist, rather than a Ph.D in an episode of season eight. George has had one appearance per year for the past several seasons.
Brian George – Now
Brian George has certainly had an interesting life. He was born in Jerusalem to parents who had emigrated from India, but was mostly raised in London. Brian has managed to build an incredible acting resume for himself, and is possibly best known for his run as Babu Bhatt on Seinfeld. In addition to The Big Bang Theory, Brian has recently been appearing as Arjun Avasarala in the series The Expanse, a role he began playing in 2015.
Kate Micucci as Lucy – Then
Lucy and Raj first meet at Stuart’s comic book store during a singles event he threw in honor of Valentine’s Day. Like Raj, Lucy also suffered from severe social anxiety to the point that she would often run out in the middle of their first few dates without so much of a hint as to her intentions. They began their relationship in season six, but got off to a rocky start as Lucy needed to the relationship to progress more slowly than it was.
Kate Micucci as Lucy – Now
Kate had been working as an actress for a while prior to being cast on The Big Bang Theory, with roles on Scrubs, ‘Til Death and Motorcity. She has also done an extensive amount of voiceover work for animated features and television shows including Clayface in Lego Batman Movie. Micucci is also one half of the musical comedy duo that is known as Garfunkle and Oates. Recently, she’s been voicing Sara Murphy in Milo Murphy’s Law.
Kaley Cuoco as Penny Hofstadter – Then
Penny is the only one of the girls who has been on The Big Bang Theory since the pilot first began airing in 2007. A very pretty, aspiring actress who financed her ambitions by working at The Cheesecake Factory. Leonard developed a crush on her almost immediately, but never expected her to return his affections. To his surprise, Penny also developed feelings for Leonard and after several road blocks to their relationship, they eloped in Vegas in the ninth season.
Kaley Cuoco as Penny Hofstadter – Now
Kaley Cuoco started acting as a teenager when she was cast as Bridget Hennessy, John Ritter’s daughter in the sitcom, 8 Simple Rules for Dating My Teenage Daughter. Kaley is one of the best paid female actress on television right now, though that list is still topped by Sofia Vergara. Kaley’s personal life hasn’t been quite as smooth as Penny’s, but she’s still doing pretty well for herself with a $900,000 per episode paycheck for the upcoming seasons.
Melissa Rauch as Bernadette Wolowitz – Then
We’re first introduced to microbiologist Bernadette in season three when Penny offers to set her up with Howard. The pair struggled to find common ground early in their relationship, until Bernadette realized that Howard’s mother was similar to her own. The two eventually married, making Howard the first of the gang to settle down and to start a family. Bernadette quickly became an integral part of the formula on The Big Bang Theory and was Penny’s first regular female companion on the show.
Melissa Rauch as Bernadette Wolowitz – Now
Melissa Rauch got her start working as a stand up comedian in New York City, while she studied acting at Marymount College. Though she had performed a successful solo show in New York City, The Big Bang Theory was her breakout role. During the course of her run on The Big Bang Theory, she has also had roles in several other TV shows and films, including True Blood and The Bronze. She also voiced Francine in 2016’s Ice Age: Collision Course.