Mark Harmon Returns to NCIS Franchise with Callback to His ‘Early Days’ in Rare Cameo

Warning: Spoilers ahead for NCIS: Origins!

Leroy Jethro Gibbs looked back at his Origins — this time on camera.

Mark Harmon reprised his role as the beloved special agent on Tuesday, Nov. 11 during a NCIS crossover event that spanned decades between the original and prequel series. It marked the actor’s on-screen return as Gibbs following a cameo in the prequel’s 2024 debut. He first originated the character for 18 seasons on NCIS before departing in 2021.

Appearing as Gibbs during the opening of Origins episode “Funny How Time Slips Away,” Harmon, 74, reflected on three decades in the business. In the scene, Gibbs poured himself a drink and recalled his “hell of a long time” on the job. “Lately, I’ve been thinking a lot about those early days, back when I was still cutting my teeth,” the character said.

After his nostalgic narration, Gibbs was seen speaking with a dog on the other end of his living room. “Over the years, the outside changes. But inside, you still feel all the same things. You’ll see,” the character said while making eye contact with the pup.

He added, “I don’t know how you ended up here in the middle of nowhere, but I’m glad we found each other. Nick of time for you too, bud, a big storm’s coming. I’m Leroy, by the way, what are we gonna call you?”

Then, while Willie Nelson’s “Funny How Time Slips Away” played in the background, Gibbs brings up an old friend of his before looking at some old photos of colleagues. “You know, a long time ago I worked with a dog that had a first and a last name. Special agent Gary Callahan. A good guy, just like you. I was lucky, I worked with a lot of good guys. Three decades, hell of a long time,” he said.

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After the heart-to-heart with the dog, Harmon de-ages and transforms into Austin Stowell’s younger version of the character thanks to some special effects. That’s when the Origins episode really kicks off, following the mysterious death of a California naval officer in the ’90s. The investigation gets a new set of eyes on it in “Now and Then,” the second-part and NCIS half of the two-part crossover.

The Origins episode also ended with a nod to Harmon’s appearance, with Kyle Schmid’s Origins character, Mike Franks, seen aging forward into Muse Watson’s older portrayal of the character on NCIS. “Three decades. That’s a hell of a long time,” Harmon narrated as the elder Gibbs. “Over the years, the outside changes, but inside, you still feel all the same things.”

Harmon has largely remained off screen in the NCIS universe in recent years but has still served as executive producer of both shows and the narrator of each episode of Origins. 

Co-showrunners and executive producers David J. North and Gina Lucita Monreal previously said in an October press release that Gibbs was “no longer alone” after disappearing to Alaska in pursuit of solitude. Well, it appears he found a friend in his new K-9.

“We know how much fans have missed seeing Mark and have wondered what Gibbs is up to today,” they said at the time.

“They continue to push boundaries and dive deeper into the characters’ backstories,” Harmon added. “They came to me with an idea for Gibbs that I liked, and it seemed like a good time to check in with him. I hope fans enjoy it.”

Speaking with The Wrap about his latest Origins appearance as Gibbs, Harmon called it “interesting to be able to reveal a glimpse of how he is living.” He added that the end result “made me smile,” explaining that “it’s a very short little bit, but the audience will get a chance to know things about him that they don’t know already.”

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NCIS: Origins airs Tuesdays at 8 p.m. ET followed by NCIS at 9 p.m ET on CBS.