Are David McCallum And Brian Dietzen Close In Real Life?

David McCallum and Brian Dietzen have been brightening up our weeks with the wit and humor of Dr. Donald "Ducky" Mallard and Dr. Jimmy Palmer on "NCIS" for the better part of two decades now. But McCallum almost didn't get his right-hand man. In May 2004, about eight months into Season 1, Dietzen was introduced in what was supposed to be his only "NCIS" appearance — something that played in his favor in the end. "What's funny is that because it was just a one day job, I decided to make some really bold choices when I auditioned," Dietzen told Paul Semel in 2014. After his successful audition, Dietzen was hired to share a scene with McCallum.

The interaction between Mallard and Palmer captivated producers, who asked Dietzen to return for another episode. "They liked it so much that it turned into a ten-year job," he told Semel. After playing a recurring character for eight years, Dietzen was hired as a series regular in Season 10, Entertainment Weekly reported. Dietzen still considers his first scene to be his most memorable. "I went in there, we had a nice juicy scene with David, where I was nervous, and I was working on a tape recorder. And he and I played really, really well together," Dietzen said (via Showbiz Cheat Sheet).

While actors are expected to make the chemistry between the characters appear real on-screen, it certainly doesn't hurt when the same happens off-screen — and that appears to be the case with McCallum and Dietzen. 

David McCallum and Brian Dietzen hit it off immediately, a connection that translated into how medical examiner Donald "Ducky" Mallard and his assistant Jimmy Palmer interact on "NCIS." "On screen and off that relationship has meant a lot — both with David and between Jimmy and Duckie. And that mentorship has been real, in front of and behind the camera," Dietzen told Starry magazine in 2019. Dietzen's promotion came after McCallum, who is in his late 80s, negotiated limited schedules with CBS. That way, Dietzen, who is in his 40s, started to take on a more prominent role. "Duckie is the reason why Jimmy has grown into a full-fledged medical examiner. Without his help and guidance, I don't think Jimmy would have been able to do that," he told Starry.

For his part, McCallum has learned from Dietzen's sense of humor. "What's lovely about Brian is when you're looking to find the comedy within a scene that has no comedy written into it, you just look at his eyes," McCallum said (via Showbiz Cheat Sheet). That's all it takes for McCallum to understand what's going on in his co-star's mind. "We just kind of click and know how to get that slight amusement about what we're doing," McCallum added. While McCallum is reaching the end of his career, Dietzen is confident he still has a lot more to share with us. "He's the most productive octogenarian on the planet," Dietzen told Paul Semel. 

David McCallum's Ducky Mallard and Brian Dietzen's Jimmy Palmer are famous for performing autopsies on "NCIS." From the get-go, McCallum knew he needed to actually become a pro at the ins-and-outs of the industry to be able to do his job on-screen accurately, and that involved studying pathology. "I've got about six feet of books on death on shelves in my house, going back to the earliest Chinese studies on autopsies," he told the U.K.'s Daily Record in 2013. And he didn't contain his studies to printed pages — McCallum actually made a habit of attending real-life autopsies at the Los Angeles Medical Examiner's office, he added. 

One time, McCallum invited Dietzen to one of those field trips — immediately after Dietzen's first day on the job, which, mind you, was supposed to be his only one. Mark Harmon was there to witness the interesting invitation unfold. "I remember thinking, 'Oh, David's inviting him to an autopsy' ... But he wouldn't invite him if he didn't like him and didn't find something in him," Harmon said, per Outsider. Dietzen thought it sounded like a great idea. "And they were off ... I thought, 'Wow, commitment.' And there they are," Harmon added.

Years may have passed, but Dietzen and McCallum continue to bond of their fondness for the procedure, which Dietzen showed in an October 2021 Instagram post that featured them on set. "Duck and Jimmy working together in autopsy? Yes please," he wrote.