Although now synonymous with NCIS, Mark Harmon’s path into acting wasn’t exactly straightforward.

During a recent appearance on The Fifth Column podcast, the 74-year-old reflected on the unexpected turns that led him into acting.

Before landing major roles, Harmon revealed he was working as a merchandising director, trying to build a stable career outside of Hollywood. That chapter of his life, however, never quite felt like the right fit.

“When the advertising stuff kind of stopped being… I just knew I had to get out of that and do something else, and I said that to my parents,” Harmon told hosts Kmele Foster, Michael Moynihan and Matt Welch.

“I had been in acting class, and I had been going and doing that, and I didn’t know where to go from there. I didn’t have an agent. I didn’t know what to do,” he continued.

As the son of actress Elyse Knox and football star-turned-broadcaster Tom Harmon, Mark grew up around both entertainment and sports. His first on-screen opportunity came in 1973 with a guest role on Ozzie’s Girls, a connection made possible through his sister Kristin and her husband, singer and actor Ricky Nelson, who were already part of the television world.

Still, breaking into the industry wasn’t seamless. At one point, Mark found himself watching Dragnet when he saw the studio ident for Mark VII Limited.

Acting on impulse, he tracked down the company’s number and called on a whim. On the other end was a secretary who could have easily dismissed the unknown caller — but didn’t. That moment of chance led to a conversation with Jack Webb, the man behind the company.

“We talked for a couple minutes and [Webb] said, ‘Why don’t you come in and talk to me?’” Mark recalled. “And I said ‘Okay,’ and I went into Universal, and I went into Mark VII, which at that time… Universal was a big enchilada, man.”

During their conversation, Mark noted that Webb “just kinda listened to me.” Webb pointed to the actor’s experience as a college quarterback as why he might make a good actor, noting that he “always pretended that [he] had the ball when [he] didn’t,” an element of “make believe” just like in acting.

That meeting ended up opening doors for Mark and led to a steady climb through film and television — including an early role playing Officer Gus Corbin in a 1975 episode of Adam-12.

Mark later made guest appearances on Police Woman in 1975 and Laverne & Shirley in 1976. Around the same time, he transitioned into film, appearing in projects like Comes a Horseman and Beyond the Poseidon Adventure.

Since then, he has appeared in projects like Summer School, The Presidio, Crossfire Trail and Freaky Friday.

His most defining role arrived when he was cast as Leroy Jethro Gibbs on NCIS, a character that would anchor the series for nearly two decades. Mark ultimately stepped away from the role in 2021 after 18 seasons, but has since reprised his character in a few scenes for NCIS: Origins.

“As an executive producer and dear friend, Mark continues to be an integral part of the fabric of the show. Our north star has always been staying true to our characters, and that truth has always guided the stories we tell and where those characters go,” Steven Binder, executive producer, told PEOPLE in a statement at the time of the actor’s departure.

“So regarding the future of Gibbs, as long-time fans of the show may have noticed over the years…never count Leroy Jethro Gibbs out.”

NCIS: Origins Season 3 Brings Mark Harmon Back in a Major Way

The NCIS universe just dropped one of its biggest updates yet and longtime fans have every reason to be excited. Mark Harmon is officially returning as Leroy Jethro Gibbs throughout Season 3 of NCIS: Origins, giving viewers far more than another nostalgic cameo. Instead, CBS is building an ambitious season-long mystery that ties present-day Gibbs to the events of his early years at Camp Pendleton, promising a story that stretches across the entire season.

For anyone who has followed Gibbs for more than two decades, this feels like the natural evolution of NCIS: Origins. The prequel has always honored the legacy of the original series while allowing Austin Stowell the space to create his own version of the younger Gibbs. Now, the show gets to have the best of both worlds.

Rather than simply popping in for a quick appearance, Harmon will appear in every episode of Season 3. That decision immediately makes the series feel even more connected to the larger NCIS timeline and gives fans a compelling reason to tune in each week. A season-long mystery centered around Gibbs’ past also opens the door for more emotional stories.

It’s a smart creative move because NCIS: Origins has never tried to imitate the flagship series beat for beat. Instead, it has focused on explaining how Gibbs became the disciplined investigator audiences grew to love. Bringing Harmon into the present-day storyline allows the show to bridge those two eras in a much more meaningful way.

The series has already teased that connection before. Harmon narrated every episode and made an on-screen appearance during the series premiere in 2024 before returning for the first NCIS/NCIS: Origins crossover event in late 2025. Those moments were memorable, but Season 3 is taking things several steps further.

The biggest question now becomes how the modern-day mystery connects to the events unfolding in the early ’90s. Since the story will reportedly unfold across the entire season, fans can expect clues, twists and revelations that gradually piece together another chapter of Gibbs’ history.

Austin Stowell also deserves credit for helping establish NCIS: Origins as more than a nostalgia project. Taking over one of television’s most recognizable characters was never going to be easy, yet he has steadily carved out his own interpretation without trying to copy Harmon scene for scene. Having both versions of Gibbs active within the same season creates an opportunity for the series to deepen the character instead of simply revisiting familiar moments.

The supporting cast, including Kyle Schmid, Mariel Molino, Tyla Abercrumbie, Diany Rodriguez, and Caleb Foote has also become a major strength for the prequel. Their chemistry has helped build an identity that stands apart from the flagship series while still feeling unmistakably like NCIS.

Harmon continues to wear multiple hats behind the scenes as an executive producer while narrating each episode. The creative team clearly understands what longtime fans want, but they’re also challenging themselves to tell a story that pushes the franchise forward. With Season 3 set to premiere this fall on Tuesdays at 10 p.m. ET/PT on CBS and streaming on Paramount+, expectations are officially climbing.

NCIS Star Mark Harmon’s Career Began With Roles On Multiple Classic ’70s Crime Dramas

When Mark Harmon took on the role of Special Agent Leroy Jethro Gibbs on “NCIS,” it was far from the actor’s first experience with crime dramas. Back in the 1970s, Harmon spent the first decade of his career appearing on classic TV shows revolving around law enforcement and emergency services. His second professional acting gig came in 1975 on the medical drama “Emergency!” — a series about paramedics working for the Los Angeles Fire Department. Harmon played Officer Gordon in an episode of Season 4, which was designed as a backdoor pilot for an animal control spinoff that never came to fruition.

That same year, Harmon joined an episode of “Adam-12” as Officer Gus Corbin. Harmon’s stints on crime series continued in 1975 with “Police Woman,” centering on a cop’s undercover work in Los Angeles. In a guest appearance in Season 1, Harmon portrayed the minor character Paul Donin before returning as Stanski in Season 3.

Another single-episode appearance materialized for Harmon in 1976 for NBC’s anthology show “Police Story,” where he played Officer Hazelton. His final 1970s crime drama was “240-Robert,” which followed the Los Angeles Sheriff’s Department’s search and rescue team. Harmon featured as Deputy Dwayne “Thib” Thibideaux throughout the show’s first season in 1979.

Mark Harmon’s early roles were crucial for his acting career

Mark Harmon’s transition from a UCLA college football star to a Hollywood actor was first marked by his guest roles on TV crime dramas. While trying to get his foot in the door, Harmon decided to call up “Emergency!” and “Adam-12” creator and executive producer Jack Webb — who also owned the shows’ production company Mark VII Limited. Harmon described the conversation on the podcast “The Fifth Column”: “We talked for a couple minutes, and he said, ‘Why don’t you come in and talk to me?’ And I said ‘OK,’ and I went into Universal, and I went into Mark VII.”

That phone conversation resulted in Harmon’s appearances on Webb’s crime procedurals, in addition to other 1970s shows. With more than a few credits to his name at the time, Harmon went on to have his breakout role as Dr. Robert Caldwell on the medical drama “St. Elsewhere” in 1983. He then made an even bigger name for himself on “NCIS” over 19 seasons, from 2003 to 2022, before shaking up “NCIS” with his exit.

Meet Mark Harmon’s two children with wife of 39 years – including actor son who starred on NCIS

Mark Harmon is married to Mork & Mindy actress Pam Dawber, and the pair welcomed two sons who have both followed in their parents’ footsteps

A merican actor Mark Harmon is best known for his leading role as Leroy Jethro Gibbs on NCIS, as well as the lovable, fatherly figure Ryan in Freaky Friday.

While Mark provides a warm, steady presence on screen, he is also a grounded husband and father to his own family off-screen.

Although Mark, 74, grew up with parents in the public eye – his mother, Elyse Knox, was an actress, while his father, Tom Harmon, was a football player and broadcaster – he and his actress wife Pam Dawber (Mork & Mindy) tend to keep their private life out of the spotlight.

Speaking to TV Insider in 2017, Mark explained: “It’s not even a choice. It’s who we are. We stay home. A lot. I’m not a Twitter guy or a Facebook guy. Our sons aren’t into that either. Pam and I have both made a living in this business, and still, there’s a part of that that’s just not natural.”

The Hollywood couple tied the knot in 1987 and are parents to two sons, Sean and Ty, both of whom have followed in their parents’ footsteps into the showbusiness world. Keep reading to find out more about Mark Harmon’s children – including one who even cameoed as him on NCIS…

Who is Sean Harmon?

Mark’s eldest son is Sean, 38, who was born on 25 April 1988 in Burbank, California. After starting out as a stunt coordinator and performer, Sean followed in his father’s footsteps – quite literally – by becoming an actor.

“Both of my parents are actors and my grandmother before my dad,” Sean told Stunt Hustle. “I went to film school here and have pretty much wanted to be involved in the industry for as long as I can remember.”

In 2008, Sean even appeared as a younger version of his father’s character, Leroy Jethro Gibbs, in flashback episodes of season six of NCIS. He also served as an executive producer alongside his father on the spin-off series NCIS: Origins.

Reflecting on his son’s career, Mark told Entertainment Tonight: “I’m proud of him taking his work seriously and how he approaches being an actor – not just on this show, [but] just what he has chosen to try to do in his life’s work.”

Now working behind the scenes in production, Sean is also a father to his son, Cooper, whom he welcomed with his producer partner Courtney Prather in May 2025. Courtney announced the happy news on Instagram, writing: “1 month with you. Cooper Knox Harmon ~ 5.22.25.”

Marking her husband’s birthday over the weekend, Courtney shared a picture of Sean with their son, with a caption that read: “Happy birthday to Coop’s dada, my husband, for real best friend, renovation partner in crime and loml. 10 years, 1 house bought and renovated for one million years, 3 cats, 1 baby and and so many laughs.”

Who is Ty Harmon?

Mark’s younger son is Ty, 33, who was born in LA four years after Sean on 25 June 1992. Like his family, Ty works in the entertainment industry, but this time behind the scenes as a screenwriter.

Ty teamed up with his brother on a short film called Catholic Schoolgirl Chainsaw Showdown in 2012, and has credits on Masters of the Air, Predator: Badlands, Venom, The Lord of the Rings: The Rings of Power and Thor: Love and Thunder. His latest project has been on Apple TV’s sci-fi series For All Mankind, starring Joel Kinnaman and Sean Kaufman.

While Ty tends to keep his private life out of the spotlight, he is married to his wife of five years, Madeline Harmon, whom he has shared photos of on Instagram.

Mark consistently sings his son’s praises, telling Entertainment Tonight: “I’m proud of both our boys, and they work hard at what they do and I’m proud that they get up in the morning and try to do that every day.”