Still one of the best sitcoms about geeks, nerds, and social outcasts, “The Big Bang Theory” boasts many of the medium’s most iconic characters: Sheldon, Leonard, Howard, Penny, Amy, Raj, and Bernadette. But over its 12 seasons on the air, “The Big Bang Theory” had a broader secondary cast that made us laugh just as much as the show’s main featured players. 

Some of these standout side characters were only in a handful of episodes, while others may have been briefly promoted to series regular. Either way, they were rarely the star but always shined, adding side-splitting comedy in places you might not expect. So while most of the attention is understandably on the show’s bigger names, there’s a laundry list of secondary characters that deserve recognition. From awkward neighbors to overbearing moms, here are our favorite 15 secondary characters from “The Big Bang Theory,” ranked from worst to best.

A somewhat more experienced scientist who works at Caltech alongside Sheldon (Jim Parsons) and Leonard (Johnny Galecki), Barry Kripke (John Ross Bowie) is probably best known for sounding like Elmer Fudd (who ranked pretty high on our list of best “Looney Tunes” characters). Of course, his lack of self-awareness is a persistent source of charm.

Kripke is a rival to Sheldon and the gang on many an occasion, including in his first appearance where he competes in a robot tournament against them. He also hits on Penny (Kaley Cuoco) — much to Howard’s (Simon Helberg) chagrin — and gets involved with prank wars in the episode “The Vengeance Formulation.” Eventually, though, Barry and Sheldon become friends of a kind — or perhaps frenemies might be the better term. Barry is invited to Sheldon’s birthday more than once (including a Zoom gathering in 2020). 

However you classify them, though, Sheldon and Barry have a begrudging respect for one another, and it’s that respect — and mutual loathing — that makes Barry’s appearances so entertaining.

It’s not often that a real-life personality becomes a persistent guest star on a hit series. But “The Big Bang Theory” defied convention by casting renowned physicist Stephen Hawking as himself. And while he’d already guest-starred in a 1992 episode of “Star Trek: The Next Generation,” Hawking’s role in “TBBT” was no mere cameo. 

Hawking was one of Sheldon’s idols growing up, and he got to meet him as a child (even if it did create a plot hole on “Young Sheldon”). And as an adult on “The Big Bang Theory,” Sheldon has the honor of calling him a friend. In real life, Hawking was a graduate of CalTech, where Sheldon studies, and the two bond over their love of science.

Hawking later appeared — in voice-over or on a video screen — in several more episodes, with Hawking and Sheldon maintaining their friendship online. The scientist returned to join the gang in “The Proposal Proposal,” helping Sheldon to get up the nerve to ask Amy to marry him. Suffice it to say, it’s always a treat when Professor Hawking is around.

“The Big Bang Theory” has seen plenty of first-rate comic guest stars, and quite a few of them turned into recurring roles. That was the case for both members of the internet comedy duo Garfunkel and Oates. But Riki Lindhome’s Dr. Nowitzki didn’t impress as much as Kate Micucci’s Lucy, who turns up first in the Season 6 episode “The Tangible Affection Proof.”

Raj meets Lucy at a singles event … at a comic book store. For that alone, they seem like they might be a good match, and her awkward social anxiety seems to be another thing they have in common. Together, the pair gets into quite a few hilarious hang-ups and strange situations, but in the end, neither is ready for this kind of serious relationship and they ultimately call it quits. Between her endearing awkwardness and Micucci’s pitch-perfect performance, though. it’s hard not to get a little smile on your face when Lucy shows up.

Over the course of “The Big Bang Theory,” we watched as the cast of characters all find their true loves. Comic book store owner Stuart Bloom — who we’ll get to later — finds his partner in Denise (Lauren Lapkus), a woman he meets when he hires her to be the new assistant manager of his shop. At first, Denise merely impresses the wider cast with her expert knowledge of movies and comic books, but quickly becomes a fan favorite and before long, she and Stuart are an item.

While Stuart is eventually bumped up to main cast member later in the show’s run, Lapkus remains a guest star throughout the series, but fans have always adored the pairing. Of course, Lapkus is about to get a whole lot more attention for her role as Denise since it was recently announced that the duo will be getting their very own spin-off series.

Sheldon’s twin sister Missy Cooper (Courtney Henggeler) doesn’t appear in as many episodes as she probably should have — and that goes doubly for her younger self (Raegan Revord) on “Young Sheldon” — but she’s probably one of the more important secondary characters. As Sheldon’s almost literal other half, Missy arguably had a bigger impact on him than any other side character other than his mother (who we’ll get to later). The fact that she’s nearly Sheldon’s polar opposite also makes her one of the most compelling characters in the entire series when she does appear.

Because she’s Sheldon’s opposite, Missy is outgoing, a real social butterfly. She’s prone to emotional outbursts but is also incredibly charismatic, attractive, and likable, which has men falling over for her attention. Because they’re so different, Sheldon and Missy have a difficult relationship, but as twins, they still share an unshakable bond. Their push-and-pull relationship is always a source of great comedy as Sheldon seeks to tame her in the hopes of playing protective brother to a woman who clearly doesn’t need his help. 

Bob Newhart turns up on “The Big Bang Theory” in the role of Arthur Jeffries, another childhood hero of Sheldon Cooper’s. Jeffries isn’t a real celebrity, though, he’s a fictional one. He’s the star of the long-running science TV series “Professor Proton,” a children’s staple in the world of “TBBT.”

“Professor Proton” is a stand-in for similar real-life shows like “Mr. Wizard” or “Beakman’s World.” It was hosted by the charismatic Dr. Arthur Jeffries, and it was this show that helped inspire Sheldon and his friends to become scientists. But when they finally meet Jeffries, in the episode “The Proton Resurgence,” they discover that Jeffries has little in common with his on-screen persona: He’s a bitter, jaded old man with little interest in science anymore because after his show, he’d lost the respect of his scientific peers and was forced to do appearances at children’s events.

Though not the kind of cynical character you’d expect to love, Bob Newhart makes Jeffries impossible to hate, and he earned an Emmy for his performance as Proton in 2013. His final on-screen guest appearance came after Jeffries’ death, when Newhart showed up as a “force ghost” ala Obi-Wan Kenobi, dishing out advice to Sheldon Cooper. 

Who doesn’t love Wil Wheaton? Other than Captain Picard perhaps, who famously told Wesley Crusher to “shut up” on “Star Trek: The Next Generation.” But it’s that role that made Wheaton another idol of avowed Trekkie Sheldon Cooper. After a guest appearance in the episode “The Creepy Candy Coating Corollary” in 2009, Wheaton returned for another 16 episodes, also playing himself in all of them.

In Wheaton, Sheldon finds a kindred spirit: A child prodigy of sorts who battled insecurity and often felt out of place. The pair of sci-fi nerds revel in their geekiness together, while Wheaton’s “Trek” family allows Sheldon to rub elbows with the stars (William Shatner, Brent Spiner, and LeVar Burton had separate cameos alongside Wheaton during his stint on the show). Famously, Wheaton even dressed up as Mr. Spock to razz “Star Wars” fans at a movie premiere of “The Force Awakens.”

Effortlessly endearing with an energy that makes it hard not to be happy when he’s on-screen, Wil Wheaton is probably the most fun celebrity guest star the show ever had.

Another sitcom legend, Sara Gilbert is arguably best known for playing Darlene Conner on the late ’90s classic “Roseanne” and its far more recent spin-off, “The Conners.” On the former series, her character dates a quirky oddball named David Healy, played by future “Big Bang Theory” star Johnny Galecki. So when Gilbert joined him on “TBBT” in the role of Leslie Winkle it, was a reunion of sorts, though she doesn’t serve as Leonard’s committed girlfriend this time, but rather a colleague at CalTech.

Winkle is an experimental physicist, and while she experimented with dating Leonard — first with a kiss and later with a quasi-relationship — they never really worked out romantically. Nevertheless, it’s Winkle’s deadpan sense of humor and her embittered relationship with Leonard’s best friend Sheldon that make her shine. You see, Winkle is a bold, straight shooter and never afraid to criticize Sheldon’s wilder theories, nor hesitant to confront him on his smug behavior. She also seems to enjoy mocking Sheldon at any chance she can get, affectionately calling him “dumbass” more than once. As the show’s loveable curmudgeon, Winkle has always been a favorite, and her dry wit was the perfect complement to the zanier antics of the main cast.

Raj’s on-again, off-again relationship with Lucy hits a snag at one point, and her name is Emily Sweeney (Laura Spencer). After ending things with Lucy, Raj meets Emily on a dating website and the two eventually become a perfectly awkward item. While she doesn’t wind up with Raj for good, most fans probably agree that Emily was the best love interest he ever had, and maybe even one of the best love interests on the show, period.

Of course, Emily isn’t without her oddball quirks, like her obsession with darkness and death, but it’s those kinds of eccentricities that make characters on “The Big Bang Theory” so much fun. And her contrast with Raj’s more innocent nature just makes their chemistry all the more hilarious as her wickedly dark sense of humor leads to more than one funny mix-up. Unfortunately, after being bumped up to series regular in Season 9, Spencer all but left the series thereafter — likely due to her joining the cast of “Bones” in a more significant role (see where she ranks on our list of best “Bones” investigators here).

Like any long-running sitcom, “The Big Bang Theory” brought in plenty of big comic names for guest spots. In 2013 they cast comedian Brian Posehn and unlike so many guest stars, he wound up returning again and again because he and his character was just so damned good. That character was Bert Kibbler, CalTech’s Professor of Geology, a lovelorn academic who works at the university alongside Sheldon Cooper.

Equally as awkward as anyone else on the show, Kibbler is constantly chasing after women who have no interest in him. Sure, he may be problematic — constantly hitting on women who are already married — but don’t hold that against him, because he’s really a good dude, just one that has no luck with the ladies. And with his own unique sense of humor, Kibbler somehow manages to make the world of rocks exciting. After all, who doesn’t love a good rock show?

Failed artist and graduate of the Rhode Island School of Design (which most people familiar will know as ‘Rizz-Dee’), Stuart Bloom (Kevin Sussman) had high hopes of being a comic book artist but ended up owning a comic book store. Like most characters in the series, Stuart is socially awkward — painfully so at times — with a longing for love that for a long time goes unfulfilled. But what many fans really feel for Stuart is a kind of kinship that can’t often be found among the other men in the main cast. Unlike Sheldon, Leonard, Howard, and Raj, he’s very rarely bitter or critical of others and is often seen as the softie of the group — and that’s exactly why we love him so much.

A true fan-favorite, Sussman imbued him with endearing qualities that might have been tough for anyone else, and his performance practically forced the writers to keep him coming back. Eventually, Stuart did find love with his assistant manager Denise, and together they’ll be headlining their own show for good reason; If there’s any secondary character who deserves their own spin-off, it’s certainly Stuart.

Some of the best secondary characters on “The Big Bang Theory” are the mothers of the main cast of characters, and that begins with Beverly Hofstadter, played by comedy icon Christine Baranski (who also starred on “The Good Wife”). The mother of Leonard, Mrs. Hofstadter is a neuroscientist and psychiatrist with an extremely analytical mind and a cold and calculated worldview. It may be where Leonard gets his brains, but he (and his father, played by Judd Hirsch) are often at odds with her over her lack of emotion.

For most in the cast of “The Big Bang Theory,” having a big brain is usually accompanied by timidness or social awkwardness. Not so with Mrs. Hofstadter, who is never afraid of dealing with others — probably because it’s others who are afraid of dealing with her. And that’s precisely why we love her: She brings a totally different dynamic to the show when she takes center stage, causing conflict by being able to read Leonard and his friends better than anyone, often making pointed observations about them that they don’t necessarily want to hear.

Every sitcom needs an absent-minded bozo meathead, be it Puddy on “Seinfeld,” Joey on “Friends” or ‘Meathead’ on “All in the Family.” On “The Big Bang Theory,” the resident dumbbell is Zack Johnson (Brian Thomas Smith), who enters the picture as Penny’s boyfriend — and his presence isn’t appreciated by Sheldon and Leonard. Often referred to as Penny’s “on-again/off-again” boyfriend, Zack nevertheless becomes her husband in a shotgun wedding in Las Vegas (though they both regret it).

An early obstacle to Sheldon in his romantic pursuit of his beautiful neighbor, Zack is just what the show needs from time to time. The friendly sparring between Zack and Sheldon and his friends is pitch-perfect, with his dashing good looks typically attracting women, much to the gang’s annoyance. It’s worth mentioning, though, that most of those women are instantly turned off by his lack of intellect, which is probably the only reason that Sheldon doesn’t absolutely despise him. For us, he’s the idiot we love to hate, and one who thankfully doesn’t get the girl in the end. But when he does show up, you always know you’re in for a laugh.

We said the parents of the main cast were some of the best secondary characters on “The Big Bang Theory,” and there are many who’d argue that Mary Cooper (Laurie Metcalf) should top TheShockNews. We don’t give her the top spot, but it’s awfully close, and it’s largely thanks to Mercalf’s performance. The “Roseanne” alum plays the loving but somewhat meddling matriarch of the Cooper clan, equal parts doting caregiver and worried mother, specifically when it comes to Sheldon.

Always there for her special little guy, Mary Cooper comes to Sheldon’s rescue whenever he’s in trouble: When he loses his job or when his relationship is on the rocks, mamma Cooper is the mother we all wish we had. That doesn’t mean they don’t get on each other’s nerves — quite the contrary — but the love between them is never in doubt, and the chemistry between Metcalf and series star Jim Parsons is impeccable. 

Even if Mrs. Cooper doesn’t top our list, she and Sheldon might be the best on-screen mother-son duo in sitcom-land. That said, they get a run for their money in “Young Sheldon,” where star Iain Armitage and a younger Mrs. Cooper — played by Metcalf’s real-life daughter Zoe Perry — are just as good.

Ironically, the best secondary character on “The Big Bang Theory” is someone we (almost) never saw. Just one in a long line of TV characters who never showed their face on-screen, Howard’s mother Debbie Wolowitz exists only in the form of the disembodied voice of Carol Ann Susi. The actor was in a whopping 40 episodes of the series, delivering some of the funniest moments of its run despite not appearing physically on-screen.

Unlike Mary Cooper, Mrs. Wolowitz is hardly the kind of loving, supportive mom a kid needs. Instead, she’s an overbearing, overprotective, obnoxious mother who wants the best for Howard but isn’t sure he deserves it. Quick to judge and quicker to make a stinging joke at her son’s expense, she may not be very nice at times but that’s often the best source of comedy. The fact that she can be so utterly hilarious without ever being physically present, too, just makes it all the more impressive.

Sadly, Susi passed away in 2014, and Mrs. Wolowitz followed suit the next year on “The Big Bang Theory.” But to make sure she was always there, she had a photo of her placed on the household refrigerator, marking the first time viewers saw Susi as Debbie Wolowitz.