If you’ve spent any time bingeing Cobra Kai, you’ve probably found yourself wondering about the math. We see Samantha LaRusso navigating high school drama, dojo rivalries, and the general chaos of being a teenager in the Valley. But if you look closely, there’s a level of poise—and let’s be honest, a certain "adultness"—that makes you realize she’s definitely not fifteen.
So, how old is Mary Mouser?
Right now, as we move through January 2026, Mary Mouser is 29 years old.
She was born on May 9, 1996. That means she’s closing in on the big 3-0 this spring. If that feels like a shock compared to her on-screen persona, you aren't alone. In the world of Hollywood, "teenagers" are almost always played by people who can legally buy a drink, but Mary’s age gap is one of the more interesting ones in the Cobra Kai cast.
The Timeline: When the Gi Doesn't Match the Birth Certificate
Mary started her journey as Sam LaRusso back in 2018. At that point, the show was a YouTube Red original (remember those?). When the cameras first started rolling for Season 1, Mary was actually 21 years old.
Think about that for a second.
She was playing a 15-year-old high schooler while she was technically old enough to have finished a four-year college degree. By the time the show exploded on Netflix and reached its final seasons, that gap only widened. In the most recent arcs of the show, Sam is roughly 17 or 18, while Mary is pushing 30.
Why the Age Gap Actually Works
Honestly, casting older actors for teen roles is a tactical move. The filming schedule for an action-heavy show like Cobra Kai is brutal. You’ve got stunt coordination, intense choreography, and long hours that would be a nightmare to navigate with the strict labor laws governing actual minors.
Mary has often talked about the physical toll the show takes. Being in her mid-to-late 20s during the height of the series allowed her to handle the physical demands of those high-stakes karate tournaments with a level of professional maturity that a 15-year-old might struggle with.
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Plus, there's the Ralph Macchio factor.
It’s actually a bit of a Karate Kid tradition. When the original movie came out in 1984, Ralph Macchio was 22 playing the "kid" Daniel LaRusso. Mary is basically just carrying on the family legacy of looking way younger than her ID says.
Life Before the Valley
While most of us know her as Daniel LaRusso’s daughter, Mary Mouser didn't just fall into the spotlight with a karate gi on. She’s been working since she was a literal child.
She’s originally from Pine Bluff, Arkansas. Her career actually kicked off when she was just six years old, working as a photo-double for Abigail Breslin in the M. Night Shyamalan thriller Signs.
Before she was Sam, she was:
- Lacey Fleming in Body of Proof (she did over 40 episodes of that).
- The voice of Eloise in Me, Eloise.
- Kelly Gibbs in NCIS.
- She even did a stint on Scandal as Karen Grant.
By the time she landed Cobra Kai, she had more than 50 credits to her name. She wasn't some newcomer; she was a seasoned pro who happened to have a "baby face" that worked perfectly for teen drama.
The Real-Life Battle: Type 1 Diabetes
One thing that makes Mary’s age and career even more impressive is something she’s been dealing with since she was 13. Just after her thirteenth birthday, she was diagnosed with Type 1 Diabetes.
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She’s been incredibly vocal about this. In interviews and on her social media, she describes the diagnosis as a "total life-shifter." She has to manage her blood sugar levels constantly, which is hard enough for a normal person, let alone an actress doing roundhouse kicks in the Georgia heat.
On set, she carries a "diabetic bag" that stays close by. It’s got her insulin pump, snacks for when her sugar drops, and all the necessary tech. She’s become a huge advocate for the T1D community, working with JDRF (Juvenile Diabetes Research Foundation) to show kids that a diagnosis doesn't mean you have to stop chasing big, physical goals.
The "Oldest" Kid in the Dojo?
It’s a fun piece of trivia: among the main "kid" cast of Cobra Kai, Mary is actually the oldest.
She’s older than Xolo Maridueña (Miguel), Tanner Buchanan (Robby), and Peyton List (Tory). In fact, she’s about five years older than Xolo. When you see them on screen together, the chemistry is so good that you'd never guess there’s half a decade between them.
Quick Age Comparison (As of Early 2026):
- Mary Mouser: 29 (Born 1996)
- Peyton List: 27 (Born 1998)
- Tanner Buchanan: 27 (Born 1998)
- Xolo Maridueña: 24 (Born 2001)
It’s kinda wild to think that while Sam and Miguel are figuring out their prom dates, Mary is technically closer in age to some of the "adult" characters' real-life ages than she is to a real high schooler.
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What’s Next for Mary Mouser?
As the Cobra Kai era winds down and Mary enters her 30s, the big question is where she goes from here. She’s spent years being "the teenager," but her recent work suggests she’s ready to move into more adult-centric roles.
She has a massive following (millions on Instagram and TikTok) and has built a brand around authenticity, especially regarding her health journey. Whether she stays in the action genre or moves back into procedural drama like her Body of Proof days, she’s got the range.
If you’re looking to follow her journey or keep up with her advocacy, here’s how to stay in the loop:
- Watch her YouTube channel: She’s surprisingly active there, posting vlogs about her life and her T1D management.
- Follow her health advocacy: Keep an eye on her work with Tandem Diabetes Care; she often speaks at conferences for young people with diabetes.
- Revisit the early roles: If you only know her as Sam, go back and watch Body of Proof. It’s a totally different vibe and shows her growth as a performer.
Mary Mouser might be 29, but in the hearts of fans, she’ll always be the girl who proved that the LaRusso legacy was about more than just a famous last name. She’s a veteran of the industry who survived the transition from child star to adult actor—a feat that’s arguably harder than winning the All-Valley Tournament.
Next Steps for Fans: If you're interested in how the show handles the age gaps, check out the behind-the-scenes footage of the stunt training. You can see Mary and the rest of the cast working with the performance team to make those fights look authentic, regardless of their real-world ages.