Brian Dietzen Recalls David McCallum Being Reason He’s on the Show

Between seasons of NCIS — the long-running CBS drama returns in fall 2026 for its 24th — fans can learn more about their favorite franchise with the podcast hosted by Brian Dietzen and Diona Reasonover. And for the Tuesday, June 9, episode of NCIS: Partners & Probies, their guest was Adam Campbell. (As is revealed during the conversation, this was filmed right after he shot NCIS Episode 500 and prior to his return to Origins being revealed.)

Having the actor who plays the young version of Ducky, of course, led to the stars remembering their time with David McCallum, who originated the role in the backdoor pilot episodes of JAG and starred as the character on the mothership until his death in September 2023. The series wrote in his passing with a very touching, powerful tribute episode, co-written by Dietzen, who plays Dr. Jimmy Palmer, first introduced as Ducky’s assistant near the end of Season 1. He came in to replace Gerald (Pancho Demmings) in what was initially thought to be a guest spot. Instead, it became much bigger, with Dietzen one of two cast members from Season 1 (the other being Sean Murray) still on the show today.

“David was a mentor and a friend to me,” Dietzen said on the podcast. “He’s the reason I’m on the show. I guest starred on the show for an episode and because the two of us had chemistry and we hit it off, the producers could see that, the network could see that, but most importantly, David could as well. And he said, ‘I want to do scenes with you.’ He actually said that to me, and that meant a hell of a lot, coming from him. We proceeded to then do scenes together for the next 18 years.”

He added, “I credit him with with keeping me around.” It had been a “one day guest star” role with the possibility of him coming back. “Then it was the next week I came back and then the week after that and then I kept showing up and they kept giving me lines.”

They didn’t work together as much once McCallum started doing fewer episodes a season and NCIS transitioned Ducky from chief ME to historian.

“We would touch base a little bit, but we wouldn’t really have those long scenes where he had those drawn out diatribes and I was sitting there learning from him,” Dietzen explained. “Just an incredible guy and the character that he created — when I say foundational, if you think of the beginnings of NCIS, of course, you think of Leroy Jethro Gibbs [Mark Harmon], you think of Abby Sciuto [Pauley Perrette], you think of Tony DiNozzo [Michael Weatherly], you also right there think of Ducky, you think of the Elder Statesmen who always had a story, always had a tale, always had a lesson for everybody on the show. When you say we miss him terribly, boy, that’s an understatement because he is a force of nature and also incredibly kind person and a hell of an actor.”

While Reasonover admitted she was “intimidated” working with McCallum, with whom she shared her first scene on the show, Dietzen came in without having watched The Man From U.N.C.L.E. “I’d not really focused on him as an actor, right? So, I came in just going this guy’s he’s really good at acting,” he laughed on NCIS: Partners & Probies. “Then I discovered his back catalog of all of his work and I’m like, I am working with television royalty here, like an absolute legend. And of course, my respect for him … just went through the roof after that. But it was wonderful because every time I worked with him, it was just two actors doing their thing. There was no hierarchy to it. He was such a giving performer and scene partner.”

Thanks to all those scenes they did have together, Dietzen also has moments he can look back on with those episodes. “I’m not Jimmy and he’s not Ducky, but those are extensions of ourselves,” he said. “That friendship is actually a reflection and a genuine extension of what we had in real life. So, I’m very thankful that we had it.”

NCIS, Season 24, Fall 2026, Tuesdays, 8/7c, CBS