Jimmy Palmer works alongside Donald "Ducky" Mallard as the assistant medical examiner as part of the NCIS crew.
Palmer first showed up as a temporary replacement medical examiner when his predecessor, Gerald Jackson, was injured as a result of a gunshot from a terrorist.
He has a deep affection and respect for Ducky, and to a certain extent has mimicked him by talking to the dead. Although his version of this behaviour is a little more ribald than Ducky's.
When Ducky suffered a heart attack on a beach, Palmer met up with him at hospital. Palmer reluctantly took over Ducky's duties and was relieved when his boss finally recovered and was able to resume his work.
Tony DiNozzo often refers to Palmer as the "autopsy gremlin".
Palmer enjoys telling stale jokes, and becomes nervous and awkward when Gibbs enters the room.
Jimmy is married to Breena Slater. As a result of their inability to conceive, they are hoping to adopt a child.
In NCIS Season 11 Episode 11, he and Breena met up with a prospective birth mother.
Palmer: No. I don't want to.
Ducky: You don't want to what, Mr. Palmer?
Palmer: I don't want to know how much her liver weighs. I don't want to catalogue her scars. Most of all, I don't want to cut open another friend. Think I've had my limit.
Palmer: I take it you heard?
Gibbs: Mmm hmm.
Palmer: Yeah, she saw the baby and just....I guess she felt the same way we felt when we first saw him. Can't fault her for that, right?
Gibbs: You should go home.
Palmer: I will. Yeah Breena and I, we just wanted to get all this stuff out of the house. You know, we wanted to give it back as soon as possible.
Palmer: Me. She's hurting too, but she is so much stronger. She's ready to try again. And me - I feel like I can't breathe. I never felt this bad in my life, Gibbs.
Gibbs: Well, just wait until it's 3:00 in the morning, and your kid's running 104. You're just getting started.
Palmer: That's the point. I'm not starting, you know? Maybe I never will.
Gibbs: Well then fight for it, Palmer! That's what you do. You fight for your family. And sometimes, you fight like hell just to have one.
Palmer: You want me to fight, I feel like I just went ten rounds with Joe Louis.
Gibbs: Do you want to be a dad, Palmer? Because right now, this is being a dad.
Palmer: Maybe I'm not ready.
Gibbs: You wouldn't feel the way you feel, right now, if you weren't ready.