Top 20 Best Young Sheldon Guest Stars

Depending on your age, you may or may not even know who ALF is. ALF, or Alien Life Form as the acronym stood for, was an alien character from a late 1980s TV show of the same name. Living with a human family, ALF was perhaps the most extreme version of a fish-out-of-water story ever told. Puppeteered by creator Paul Fusco, he appeared in a season two episode of “Young Sheldon” after Missy sends him a letter confessing her adoration for the Melmacian. Though the character has occasionally appeared in other media since his show went off the years, this was a welcome surprise.

For ‘80s kids, he was Michael Knight and drove the coolest car in the world. If you were around in the ‘90s, you probably knew him as Mitch Buchannon, always running with his colleagues along the beaches of California. But David Hasseolhoff’s resumé also includes a cameo as himself in “Young Sheldon.” During a season four episode, Georgie wants to put out an exercise video and gets the drama teacher, Mr. Lundy, to help him. The two part ways after a dispute, and Lundy seeks assistance from a much more prominent face in television: the Hoff. The tail end of the episode treats viewers to “cowboy aerobics,” featuring the man himself. It’s definitely something!

If you ever watched “MadTV” during its heyday, you undoubtedly caught the talents of Will Sasso. A hilarious comedian and actor, Sasso appeared in five seasons as a regular and multiple other times as a guest star. He’s also popped up on shows like “How I Met Your Mother”, “Modern Family” and countless others. Sasso added a slightly more reserved character to his repertoire when he popped up on “Young Sheldon” as Mandy’s father, Jim. As the owner of a local tire shop, he certainly makes an impression each time he’s on screen. We wonder if he has anything to do with how Georgie ends up becoming the tire doctor.

“The Big Bang Theory” may have featured a lot of geek culture, whereas “Young Sheldon” has tended to lean less on the nerd, and more on the family aspect of Sheldon’s life. As a result, some viewers might not have recognized Michael Trucco when he appeared in Mary’s fantasies. Sci-fi fans, however, would recognize Trucco immediately from his time on the 2004 “Battlestar Galactica” series. He also shares a special connection to the show’s predecessor, having appeared as a guest star on it as well. Anyone remember Leonard’s bromance with Dr. David Underhill? He’s the reason Penny bought Leonard motorcycle lessons!

What do the shows “Just Shoot Me!”, “Star Trek: Lower Decks”, “Hot in Cleveland”, and “Bubble Guppies” all have in common? They all featured the talents of American actress, Wendie Malick. Having got her big break on “Dream On” and the aforementioned “Just Shoot Me!”, she has been delighting audiences with her talents ever since. For poor Sheldon Cooper, Malick has appeared several times as Linda Hagemeyer. As the president of the college Sheldon is attending, she’s tasked with keeping him happy enough so he'll stick around, while simultaneously doing anything she can to get under his nerves. It’s as fun as it sounds.

Melanie Lynskey is one of those stars who has an undeniable talent, and she’s impressed us on countless occasions. Many people will remember her as Rose, the woman who had an unhealthy obsession with Charlie on “Two and a Half Men”. There’s also her more recent work as Shauna on the acclaimed “Yellowjackets.” Clearly, her resume boasts countless stage, film, and television appearances, and we never tire of watching her. Her appearance on “Young Sheldon” further emphasizes her abilities, as she portrayed a philosophy teacher who causes the title character to question the very nature of his life and everything in it. That’s no small task, yet she makes it look effortless.

She battled foes and made the hard choices as Melinda May during her time on “Agents of S.H.I.E.L.D”. Meanwhile, in the “Star Wars” universe, she became Boba Fett’s partner after initially being known as a famed assassin. She’s also been the voice of countless characters, including Disney’s iconic Princess “Mulan”. So after taking all of that on, who else could she possibly have to take on? The answer is, of course, Sheldon Cooper. The university president calls her in to settle a dispute between Dr. Linkletter and Dr. Sturgis. Sheldon is caught in the middle as Wen’s character, Dr. Carole Lee, helps calm the waters.

Mckenna Grace has been popping up on “Young Sheldon” ever since season two. As Paige Swanson, she has been a worthy adversary turned friend of Sheldon’s as the show has progressed. In one of the sitcom’s most powerful moments, we see Paige’s struggle with her parents divorce come out in literal tears, all thanks to this young actress. Given her incredible gifts, it’s no wonder we’ve been seeing more of her on film and television. “Ghostbusters: Afterlife”, “The Bad Seed” movies, and “Fuller House” are just a few in what is becoming an impressive list of credits.

Throughout the run of “The Big Bang Theory”, we often heard Sheldon refer to his neighbor Billy Sparks, who tormented him. When the spinoff prequel finally surfaced, we learned that perhaps older Sheldon didn’t remember things as well as he’d like to think. Billy, albeit a bit clueless, seems like a decent kid. Perhaps part of that is due to his upbringing, courtesy of his father, mechanic and garage owner Herschel. Played by “Mike & Molly” comedian Billy Gardell, Herschel is one of the sitcom’s best recurring characters. Though it’s a more understated role on the whole, Gardell is fully able to flex his chops and deliver at every turn.

While fans loved seeing older Sheldon Cooper have one too many on “The Big Bang Theory”, a similar scene could never happen on “Young Sheldon”. Or could it? Turns out, it sort of could. After getting to the verge of a major physics realization while unconscious, Sheldon is desperate to recreate the effects of anesthesia. He consumes a high-powered tea, and we find ourselves watching him hallucinate in his room. Among the posters on the wall, we hear the iconic Cyndi Lauper educate Captain Proton on Gotthold Ephraim Lessing. Did we ever expect to hear the “Girls Just Want to Have Fun” singer bring a poster of herself to life? No, but we’re very glad it happened — it’s pretty funny stuff!

Even if this name doesn’t ring a bell, you might still recognize Steve Burns as Steve from the Nickelodeon kids show, “Blue's Clues.” On “Young Sheldon,” Burns plays Nathan, a middle-aged comic book nerd the title character becomes friends with, and someone Sheldon’s Meemaw certainly doesn’t appreciate her grandson being around at first. Nathan ends up being a good casual friend for Sheldon, though he may be too old to be hanging out with a kid. Playing Nathan isn’t the only contribution Burns has made to “Young Sheldon” as he’s also supplied the show’s theme song, “Mighty Little Man.”

This “The Kids in the Hall” member has appeared in a few episodes playing an obnoxious wealthy businessman named Gary O’Brien. The university Sheldon attends initially wants him to dine with O’Brien in the hopes that the businessman will cut the university a big check after meeting the prodigy. However, our protagonist, not feeling that Mr. O’Brien is his intellectual equal, tells him off in blunt Sheldon-esque fashion. Foley has since returned in the role, with the character becoming even more eccentric. It’s great to watch Sheldon being forced to put up with O’Brien’s absurdity.

When Sheldon develops a pimple, the comedic duo appear, Penn as a personified version of acne and Teller as his partner, pus. Together, they break down the significance and implications of Sheldon’s situation, as Penn discusses the details in a lively manner while Teller sits quietly and plays off him. According to TVLine, series co-creator Steven Molaro and the team thought Penn Jillette would be “perfect” when deciding who to bring on as the zit. Watching the star’s over the top delivery that manages to be both obnoxious and charismatic, we would have to say this casting decision was the right call.

The late actor manages to be both intimidating and hilarious as Sheldon’s engineering professor, an armed services veteran who runs his class with discipline. At first, Sheldon appreciates this strict teaching style. But that changes once it forces him to struggle with a difficult assignment. Sheldon rarely meets his match, so it’s nice to see Reddick’s character put him in his place without breaking a sweat. It’s a long running gag in “The Big Bang Theory” that Sheldon has disdain for engineers, and Reddick’s fantastic appearance helps explain the reason why that is.

In the third season, this country music superstar made her debut on the show as June, a hairdresser and friend of Sheldon’s Meemaw, Connie. With a successful acting career which included her own popular sitcom, McEntire and her folksy, southern energy are a natural fit for “Young Sheldon” and its Texas setting. With her charming, bubbly personality on the show and in real life, Reba is always a delight to see whenever she stops by. Unfortunately, she doesn’t bring her singing talent with her, as her character can’t carry a tune in a bucket.

The comedy veteran plays Gene Lundy, an oddball drama teacher at Sheldon’s high school. Passionate about his craft, Mr. Lundy is up to play any role available, whether it’s the dark lord Satan or little orphan Annie. And he’s not afraid to ham up his performance for the crowds, either. In later episodes, the character participates in business hustles such as creating an exercise tape and pushing a cosmetics pyramid scheme. Leave it to the man who played George Costanza on “Seinfeld” to give life to a character so shameless.

Newhart reprises his unforgettable role as Arthur Jeffries from “The Big Bang Theory,” for which he had won an Emmy. In the pilot episode of “Young Sheldon,” we finally get to see Newhart play Professor Proton, the host of a science education show that Sheldon loved in his childhood. And it isn’t the character’s only appearance, either. Each time we see him, Newhart brings his classic straight-faced delivery to a man clearly living a life of quiet desperation. This is one of many callbacks that “Young Sheldon” has made to the “Big Bang Theory,” serving as a nice treat for viewers and providing a connection to the original show.

Given the kind of tough guy, underworld roles Liotta typically played, “Young Sheldon” might’ve been the last place someone would expect him to guest star. However, the “Goodfellas” was perfectly cast as Vincent, a shady bookie whom Connie runs into at a Louisiana casino. Liotta infused the part with the perfect balance of humor and grit, making us laugh while still respecting his imposing presence as he tried to shake down Sheldon’s Meemaw. This appearance gave the late actor a chance to show a side of him audiences often didn’t get to see in a lighthearted family sitcom, and it was great.

A few years after making appearances in shows like “The Simpsons” and “The Big Bang Theory,” Musk showed up in “Young Sheldon”’s first season. In a flash-forward toward the end of the sixth episode, Musk borrows ideas from a notebook that Sheldon worked on when he was young for his SpaceX company. It goes without saying, but getting a tech billionaire and one of the richest men in the world is a big boon for the show. While there’s no denying Musk is a controversial figure, he is at least able to poke fun at himself with this cameo.

One great callback “Young Sheldon” has made to “The Big Bang Theory” is having main cast members from the original show on as guest stars. Simon Helberg, for instance, has returned as Howard to notably talk about engineering – what else?! Kaley Cuoco, for her part, showed us what she could do as pool water. However, our favorite of these appearances has to be Mayim Bialik. She once again plays Amy Farrah Fowler, Sheldon’s partner, as we hear her voice in the narration. Her feisty personality is a great contrast to his stubborn attitude, and we love getting tastes of it on “Young Sheldon” just as much as we did on its predecessor.

Who’s been your favorite guest actor on “Young Sheldon”? Let us know down below.