If you’ve watched network TV anytime in the last twenty years, you’ve probably landed on NCIS. The theme, the head-slaps, the Naval Yard cases — it’s been hard to miss since the show spun out of JAG in 2003 and grew into one of broadcast’s longest-running procedurals.
When an ensemble lasts that long, it’s easy to forget these actors ever played anyone else. Here’s where a chunk of the core cast turned up before the squad room.
Mark Harmon played almost every kind of lawman
It’s hard to picture NCIS without Leroy Jethro Gibbs. Harmon carried the role from the JAG backdoor pilot through season 19 — coffee, rules, and that quiet stare.
Before the Navy Yard, he’d already lived a few careers. He was UCLA’s starting quarterback in the early ’70s, following his father, Heisman winner Tom Harmon. Acting came later, after a walk-on on the sitcom Ozzie’s Girls.
On film you’ll catch him opposite Jamie Lee Curtis in the 2003 Freaky Friday remake, and in a brief turn in Oliver Stone’s Natural Born Killers. TV built his name: four seasons as Dr. Jack McNeil on Chicago Hope, then an Emmy-nominated arc as Secret Service agent Simon Donovan on The West Wing — the role that helped land him Gibbs.
Rocky Carroll is a Tony-nominated stage actor
Carroll took over as Director Leon Vance in season five after Jenny Shepard’s death and has outlasted every previous director on the show.
Before that, he put in serious stage time. In 1990 he earned a Tony nomination for August Wilson’s The Piano Lesson; Samuel L. Jackson appeared with him in the earlier Yale Rep production and later understudied on Broadway. On screen he’s shown up in Born on the Fourth of July, Grey’s Anatomy, and Law & Order, starred with Charles S. Dutton in the early-’90s sitcom Roc, and worked with Harmon years before NCIS on Chicago Hope.
David McCallum was a 1960s pop icon
As Chief Medical Examiner Dr. Donald “Ducky” Mallard, McCallum was the squad room’s historian for decades — bow ties, digressions, and all.
Long before the autopsy bay, the Scottish-born actor was a star. He broke through in 1963’s The Great Escape opposite Steve McQueen, then became a teen idol as secret agent Illya Kuryakin on The Man from U.N.C.L.E. He kept working: The A-Team, Murder, She Wrote, and the voice of Professor Paradox on Ben 10. McCallum died in 2023 at 90, leaving one of the show’s most beloved characters behind.
Sean Murray is in the movie you rewatch every October
Murray arrived early in season one as probationary agent Timothy McGee and never left. He’d already brushed the franchise: two different guest roles on JAG years earlier.
’90s kids know him elsewhere. In 1993 he shared the screen with Robert De Niro and Leonardo DiCaprio in This Boy’s Life, then played human Thackery Binx in Disney’s Hocus Pocus — most of the runtime he’s a talking black cat, but that face stuck. Same year, he crossed paths with Harmon on the short-lived western Harts of the West.
Pauley Perrette was in one of the best rock movies of the 2000s
For 15 seasons, Abby Sciuto ran the forensics lab on Caf-Pow and goth energy.
Perrette spent the late ’90s collecting guest spots on Frasier, The Drew Carey Show, and 24. Right before NCIS she appeared on CSI. Her sharpest early film credit: radio DJ Alice Wisdom in Cameron Crowe’s Almost Famous (2000), opposite Philip Seymour Hoffman.
Emily Wickersham started in tiny credits — then prestige TV
Wickersham joined in season 11 as NSA analyst–turned–agent Ellie Bishop and stayed eight seasons.
Early work was blink-and-you-miss-it: “1998 Intern” in the Ryan Reynolds rom-com Definitely, Maybe, “Miami Blonde” in Robert Pattinson’s Remember Me. The pre-NCIS credit that counts is prestige TV — she played A.J. Soprano’s girlfriend Rhiannon across four episodes in the final stretch of The Sopranos.
Her biggest pre-NCIS breakout happened on prestige TV: she played A.J. Soprano’s high school girlfriend Rhiannon across four episodes in the final stretch of The Sopranos.
Wilmer Valderrama already had one of TV’s most familiar faces — and voices
When Valderrama joined in season 15 as undercover agent Nick Torres, audiences already knew him.
Most people clock Fez from That ’70s Show, all eight seasons. Parents in the mid-2000s heard him every morning as the title character on Disney’s Handy Manny. He’s also had a recurring arc on Grey’s Anatomy, played a vampire crime boss in the From Dusk Till Dawn series, and popped up in LMFAO’s “Sexy and I Know It” video in 2011.
Brian Dietzen ground through the early-2000s before the autopsy room
Jimmy Palmer started as Ducky’s earnest assistant and eventually became chief medical examiner; Dietzen played him for years before the opening credits caught up.
His early film résumé includes 2003’s From Justin to Kelly, the Kelly Clarkson–Justin Guarini musical that bombed. He booked NCIS the next year. Outside the show he’s written and starred in the indie Congratulations (2012) and co-written multiple NCIS episodes.
Maria Bello brought film-star weight to the team
Bello arrived in season 15 as forensic psychologist Jack Sloane with a serious movie résumé already behind her.
She broke through on TV as Dr. Anna Del Amico on ER in the late ’90s, then spent the 2000s in major films: David Cronenberg’s A History of Violence, World Trade Center, Thank You for Smoking, and Grown Ups. For anyone who rented VHS tapes around 2000, she’s permanently Lil — the sharp bar owner in Coyote Ugly.
Lauren Holly led before Vance — and owned ’90s screens first
Before Leon Vance took the corner office, Holly ran NCIS as Director Jenny Shepard for seasons three through five.
She had a strong 1990s run: Mary Swanson in the original Dumb and Dumber with Jim Carrey, opposite Harrison Ford in the 1995 Sabrina remake, Oliver Stone’s Any Given Sunday, and Mel Gibson’s ex-wife in What Women Want. Like Harmon and Carroll, she also put time in on Chicago Hope before the NCIS universe.
Twenty-plus years in, NCIS still runs on faces that feel new in the Navy Yard and familiar everywhere else. Squint at the next rewatch — you’ll catch the quarterback, the Tony nominee, the U.N.C.L.E. idol, and the kid from Hocus Pocus all in the same squad room.
