The Transformation Of Mark Harmon From Childhood To NCIS

With an impressive resume that spans several decades, Mark Harmon is best known for his portrayal of former Marine sniper turned special agent Leroy Jethro Gibbs on "NCIS." The CBS police procedural drama — a spin-off of the legal drama "JAGS" — follows members of the Naval Criminal Investigative Service as they navigate their personal and professional lives.

Harmon led the popular series for 18 seasons, captivating audiences with Gibbs' dry sense of humor, signature icy glare, and complete devotion to his team. "I was attracted by (his) flaws," Harmon said of his character in 2005. "He has lousy taste in women. He's addicted to coffee" (via USA Today).

With Harmon's admiration for his complex character and his career-defining performance, it's easy to forget just how many TV shows and movies he'd starred in leading up to the role. Now that he's officially stepping back from "NCIS" in Season 19, let's reminisce on the actor's life and career pre-Gibbs.

Mark Harmon took a rather untraditional path toward acting, though he followed in his parents' footsteps. While his mother, Elyse Knox, was an actress, his father, Tom Harmon, was a football player before becoming an actor, and later became a sports broadcaster. Like Tom, Mark was passionate about the sport and speaks highly of his father's legacy, telling Parade in 2019 that watching him broadcast games "had a certain magic."

After playing football from childhood through community college, Harmon received an offer from the University of California, Los Angeles, in 1971. He started as a quarterback for the Bruins in 1972 and 1973, leading the team through outstanding seasons. In 2019, he was awarded the National Football Foundation Gold Medal to honor his "exceptional accomplishments, unblemished reputation and for reflecting the values of amateur football." Jack Ford, the NFF Awards Committee Chairman, praised Harmon's humbleness and ability to focus on "hard work, perseverance and teamwork" (via UCLA).

"His success on the gridiron as a student-athlete and his subsequent icon status in film and television make him exceptionally well-qualified as our 2019 Gold Medal recipient," said Ford. Though he is no longer actively involved in the sport, Harmon still enjoys watching football with his family and rooting for his alma mater.

Mark Harmon had dozens of guest appearances and recurring roles early in his acting career, many of which happened to be on police procedurals that set the groundwork for his future "NCIS" success. 

His first foray into the acting world came as he began spending more time with his brother-in-law, pop singer Ricky Nelson, and his parents, Ozzie and Harriet Nelson. The musical family starred together in the 1950s sitcom "The Adventures of Ozzie and Harriet." In an interview with Parade, Harmon recalled Ozzie asking him to replace an actor on their spin-off show, "Ozzie's Girls," and said that it "changed (his) course."

Following this, he rerouted from pursuing professional football to enrolling in acting classes and booking roles in episodes of shows like "Emergency!", "Police Woman," "Laverne & Shirley," and "The Hardy Boys." Additionally, he scored the recurring roles of Officer Mike Breen in "Sam," Captain John McIntosh in "Centennial," and Deputy Dwayne Thibideaux in "240-Robert" (via IMDb). While Harmon stayed booked and busy in the 1970s, his real breakout role came in 1983.

With an Emmy nomination for his performance as Robert Dunlap in the 1977 mini-series "Eleanor and Franklin: The White House Years," Mark Harmon's career was on the upswing (via Emmys). In the 1980s, he played serial killer Ted Bundy in the mini-series "The Deliberate Stranger" to critical acclaim — earning a Golden Globe nomination for his performance — and starred in various projects like the Western "Wyatt Earp," the dark comedy "Fear and Loathing in Las Vegas," and the soap opera "Flamingo Road" (via IMDb).

However, his breakout role came in 1983 when he began acting as Dr. Robert Caldwell in the medical drama "St. Elsewhere." He portrayed the promiscuous plastic surgeon for three seasons, ending his time on the show with a groundbreaking off-screen death. His exit from the series made primetime TV history for being the first to have a character die after contracting HIV from unprotected sex (via Variety).

"At the time it was really risky, but years later it was something people talk about and remember. What they were saying about that character was simply not being done at that time," Harmon told Variety, referring to the stigma surrounding the HIV/AIDS epidemic of the 1980s. In addition to the historic role, Harmon was also named the "Sexiest Man Alive" by People in 1986.

From 1991 to 1993, Mark Harmon starred as Detective Dicky Cobb on the police drama "Reasonable Doubts," and then as the titular character in the crime drama "Charlie Grace" in 1995. Next, he joined the CBS show "Chicago Hope," in which he starred as Dr. Jack McNeil from 1996 to 2000. Along the way, he also directed two episodes of the medical drama (via IMDb).

Of Harmon's dozens of guest appearances and recurring roles over the years, his most popular is in "The West Wing." He starred in four episodes of the acclaimed political drama as Agent Simon Donovan, a Secret Service member assigned to protect C.J. Cregg (Allison Janney). Harmon praised the show's outstanding acting and writing, telling the Chicago Tribune that he didn't hesitate to accept the role. "I got a scene faxed to me by my agent late on a Wednesday afternoon, and Thursday morning I was working," he said. 

Accepting this role was huge for Harmon's career — he received a Primetime Emmy nomination for Outstanding Guest Star in a Drama Series, and caught the eye of his future boss.

After watching Mark Harmon's acclaimed guest performance on "The West Wing," producer Donald P. Bellisario brought the actor onto his legal drama "JAG," marking the first appearance of SSA Leroy Jethro Gibbs in 2003 (via Entertainment Weekly). Later that year, Harmon appeared as Gibbs on the "JAG" spin-off series, "NCIS," and the rest is history.

In 2008, Harmon went a step further and also began working behind the scenes as a producer and executive producer of the series he led (via Variety), and he later also worked as a producer on the spin-off series "NCIS: New Orleans." With nearly two decades devoted to the long-running franchise, it's not surprising that the actor decided to step back in Season 19 of "NCIS."

Despite going from a series regular to a guest star, showrunner Steven D. Binder said that Harmon will remain "an integral part of the fabric of the show." He also hinted that this isn't the end just yet, saying, "as longtime fans of the show may have noticed over the years ... never count Leroy Jethro Gibbs out," he said (via ET).