Character: Arthur Jeffries aka Professor Proton
You can’t forget Professor Proton. He’s the main reason Sheldon and Leonard wanted to be scientists. His story turned sad when he met up with the two and revealed that he wasn’t able to get work following the Professor Proton Show.
Actor: Bob Newhart
Bob Newhart is a remarkable actor and stand-up comedian. In the ‘60s, he released an album of comedian monologues called The Button-Down Mind of Bob Newhart. It reached number one on the Billboard pop chart and became a worldwide bestseller. It remains the best-selling comedy album in history.
Character: Mike Rostenkowski
Mike was Bernadette’s father. A retired police officer, he has a lot of opinions. In fact, when Howard was to meet him, Bernadette warned him not to mention gardeners, Jimmy Carter, foreigners, Sean Penn, organic food, and a ton of other things.
Actor: Casey Sander
Casey Sander is a seasoned Hollywood veteran. He’s been in the biz for over 30 years and has starred in over 300 episodes of TV, 25 movies, 18 feature films, and countless commercials. His most notable appearances include playing Wade Swodoba in Grace Under Fire and Rock Lannigan in Home Improvement.
Wyatt was Penny’s father. Naturally, he’s very caring and friendly. He tries to be Penny’s guiding hand, but he also wants her to be happy. Even though he wanted a boy, he very much loved his daughter and was super ecstatic when she started dating guys with brains.
Actor: Keith Carradine
Keith Carradine isn’t a stranger to television. On top of guest-starring in TBBT, he’s also appeared in Deadwood, Dexter, Nashville, and Madam Secretary. He’s also won a Golden Globe and an Academy Award.
Character: Dr. V. M. Koothrappali
Dr. V. M. Koothrappali is Raj’s dad. At first, he only appears in video chats, but following his divorce, he starts showing up physically in episodes. Try as he might, he couldn’t get Raj to become a doctor and follow in his footsteps.
Actor: Brian George
Raj’s dad is portrayed by Brian George, an Israeli-English actor, comedian, and singer. If he seems a little familiar, you may also be a Seinfeld fan. He played Babu Bhatt, the owner of the Dream Café, and the one that regularly called Seinfeld a “very, very bad man.”
Character: Zack Johnson
Zack Johnson was Penny’s on-again-off-again boyfriend. Technically, he was Penny’s ex-husband. Remember when they got married in Las Vegas? They may not have known that it was legal, but it sure was. The poor guy was incredibly dim-witted, but he was sweet at heart.
Actor: Brian Thomas Smith
Brian Thomas Smith’s biggest role is appearing in The Big Bang Theory, but he’s also a regular on reality game shows like Fear Factor and The Amazing Race. He’s also made guest appearances on Two and a Half Men.
Character: Priya Koothrappali
Priya is Raj’s younger sister and, for a time, she was Leonard’s love interest. Raj was pretty angry about it, but he couldn’t keep them apart. Unfortunately, the two didn’t work out anyway as she had to return to India. They attempted to do a long-distance relationship, but Leonard couldn’t do it.
Actor: Aarti Mann
Aarti Majumdar, better known as Aarti Mann, has starred in several TV shows, including Heroes where she portrayed Shaila. When she’s not in front of the camera, she’s behind it as an assistant director and writer.
Character: Mary Cooper
Mary is Sheldon’s kind, loving, ultra-religious mother, and she’s probably the only one who can keep her “Shelly” in line. In a way, she also becomes the group’s surrogate mother because she gives them wisdom they didn’t get from their own mothers (particularly Leonard).
Actor: Laurie Metcalf
Laurie Metcalf has been an actor for over four decades, and she has three Primetime Emmys under her belt. She’s also appeared in several movies, but her most memorable role is likely Jackie from Roseanne.
Character: Leonard Hofstadter
Sheldon's mostly normal (though no less nerdy) roommate Leonard provides us a more human voice. Experimental physicist Leonard Hofstadter managed to somehow withstand Sheldon's ridiculous, iron-clad 'roommate agreement.' At least, until Sheldon moved out to live with his girlfriend Amy and Penny moved in. Following that, she and Leonard finally tied the knot.
Actor: Johnny Galecki
Before he was Leonard, Johnny Galecki was first known for his role as David on Roseanne. Whenever he wasn't filming The Big Bang Theory, he performed in a duet band and worked as the executive producer and host of the prank series SciJinx.
Character: Howard Wolowitz
Howard is a character that is often the butt of jokes, and Sheldon teases him constantly for being "only an engineer." About halfway through the series, Wolowitz managed to become an astronaut and spent several episodes in space. He married Bernadette in season five, and they had two kids together.
Actor: Simon Helberg
Simon Helberg definitely is a lot less dorky than Howard and has a nicer haircut and a sense of style. Similar to Galecki and Parsons, Helberg and his wife, actress Jocelyn Towne, have gone behind the camera to launch other shows such as Need To Know, a CIA workplace comedy.
Character: Debbie Wolowitz
So we never saw Debbie Wolowitz's face, but everyone could recognize Howard's mom's memorable voice. In season 8, Debbie Wolowtiz died, and it was a majorly emotional time for everyone.
Actor: Carol Ann Susi
Carol Ann Susi was known for her memorable voice and hilarious lines on TBBT, unfortunately, we'll never hear her voice again. Susi died of cancer in 2014 at the age of 62, and the writers wrote her character off the show following her death.
Character: Stuart Bloom
Poor, poor Stuart. He’s easily stressed out, but it comes with the territory when you’re friends with both the boys and Wil Wheaton. He owns the Comic Center of Pasadena where the guys regularly visit, and episodes are almost always made better when he’s in them.
Actor: Kevin Sussman
Kevin Sussman actually did work at a comic book store before acting, so his knowledge is spot on. Other than TBBT, he’s also appeared in Burn After Reading, Killers, Almost Famous, and Wet Hot American Summer.
Character: Sheldon Cooper
A genius theoretical physicist with not-so-genius social skills, Sheldon Cooper began as a robotic, unfeeling, and neurotic character. Thankfully, over the years, Sheldon has become a little more human (though, no less neurotic). He's a weirdo, and you can't help but love him!
Actor: Jim Parsons
Thanks to his time on The Big Bang Theory, Jim Parsons is a Hollywood star. When he wasn't playing the lovable weirdo Sheldon, he's appeared in films like Hidden Figures and The Muppets. In 2017, Parsons married his long-time partner Todd Spiewak.
Character: Rajesh "Raj" Koothrappali
The unlucky-in-love astrophysicist, Rajesh "Raj" Koothrappali was Howard Wolowitz's best friend and partner-in-crime. Similar to the other characters, Raj had trouble with his love life, much of the early seasons consisted of him having to drink in order to just talk to women. At least he moved past that stage.
Actor: Kunal Nayyar
Born in London, raised in New Delhi, Kunal Nayyar moved to the United States to study business at the University of Portland. However, his passion won out, and The Big Bang Theory gave him one of his first major roles. He married fashion designer Neha Kapur in 2011 and is an experienced golfer.
Character: Emily Sweeney
In the words of Raj, Emily is scary, but it’s a cute scary. For a while, she was Raj’s main love interest. The relationship was tough since Raj wasn’t the best at communicating, but it was clear they were both trying.
Actor: Laura Spencer
Playing Emily is probably one of Laura Spencer’s biggest roles, but that doesn’t mean she hasn’t done anything else. She’s also appeared in Bones with a recurring role as Jessica Warren, as well as the web series The Lizzie Bennet Diaries.
An aspiring actress and former Cheesecake Factory waitress, Penny started off as the "dumb blonde" stereotype that lived across the hall from Leonard and Sheldon. She often acted as the voice of reason and a stand-in for the audience when it came to understanding the scientific aspects of the show. Fun fact: Penny's maiden name has always been unknown.
Actor: Kaley Cuoco
One of TV's top-paid actresses, Kaley Cuoco earned $1 million per episode. She's an avid equestrian and former accomplished tennis player. She and her husband, a professional equestrian, Karl Cook married in June of 2018.
Character: Barry Kripke
Known best in the show for his lisp, Barry Kripke is another theorist at Caltech where the main four characters work. He's constantly belittling Sheldon and trying to get him in trouble with crazy schemes.
Actor: John Ross Bowie
Without the lisp, he makes a bit more sense. John Ross Bowie found success on TV with the show Speechless and appeared on the comedies Episodes and Children's Hospital. He and TBBT co-star Kevin Sussman (who plays Stuart, the comic book shop owner) have a sitcom in development.
Character: Amy Farrah Fowler
A late addition to the series, Amy debuted as an online date for Sheldon Cooper before she became a series regular. Amy and Sheldon dated before getting married in the 11th season finale. Equally as awkward and intelligent as Sheldon, the two are a perfect match.
Actor: Mayim Bialik
Before she was Amy Farrah Fowler, Mayim Bialik starred in the '90s hit Blossom. One thing many people don't know is that she's just as brainy in real life as she is on the show. Bialik earned a Ph.D. in neuroscience at UCLA. She has been an outspoken advocate on a number of issues and has published several books ranging in topic from attachment parenting to a vegan cookbook.
Alicia was basically just meant to be a rival for Penny. She was an aspiring actress who lived in the same building who quickly gained approval from Sheldon, and Raj, Howard, and Leonard all fell hard for her. However, Penny found out that Alicia was just using the boys to help her, and she confronted her. Penny wound up with a black eye, and the boys abandoned Alicia.
Actor: Valerie Azlynn
Not near as vicious and ruthless as her character, Valerie Azlynn has been acting in small roles for various movies and TV series. In 2012, she landed a more significant role in the TV comedy Sullivan & Son, where she played Melanie Sutton.
Character: Wil Wheaton
Wheaton is the character that gets under Sheldon’s skin, especially after Sheldon confronted Wheaton at the Mystic Warlords of Ka’a game, and Wheaton lied straight to his face. He was obviously a pretty dark guy in the series, though he’s lightened up some in more recent seasons.
Actor: Wil Wheaton
In real life, Wil Wheaton is an actor who likes to stir up drama online. He’s appeared in shows and movies including Star Trek: The Next Generation, Toy Soldiers, The Secret of NIMH, and Stand by Me.
Character: Leslie Winkle
Leslie was essentially created to be the female version of Leonard, even wearing the glasses and clothes. She feuds with Sheldon throughout the entire series. Leonard and Leslie date briefly, but Howard is the one she winds up having a relationship with, though the whole thing is very one-sided.
Actor: Sara Gilbert
Sara Gilbert is probably best known for her role as Darlene Conner in Roseanne. She lives with her wife, Linda Perry, and her three children from previous relationships. Gilbert took on the role as executive producer for the Roseanne reboot, but that obviously went down in flames when the titular character/address, Roseanne Barr, came under severe controversy.
Character: Bernadette Rostenkowski-Wolowitz
Though she but little, she is fierce. Don’t let her short stature and high-pitched, squeaky voice fool you. Bernadette's a majorly tough cookie. Bernadette is known for bullying people into doing her bidding. She married Howard, had two kids, and is a super successful microbiologist. One of the best characters on the show, hands down.
Actor: Melissa Rauch
Before she landed her star role on TBBT, Melissa Rauch made several appearances on TV with small roles on The Office and True Blood. Rauch wound up making half a million dollars per episode of TBBT. Between takes, she was a successful voice actor who co-wrote and co-produced the movie The Bronze with her husband Winston.