Sean Murray talks NCIS longevity and saying goodbye to Mark Harmon as the show hits 450 episodes

NCIS airs its 450th episode tonight, and one actor has been there for (almost) every minute.

Sean Murray has been suiting up as NCIS Special Agent Timothy McGee since 2003's "Sub Rosa," the seventh episode of season 1. To celebrate the show hitting this milestone in its 20th season, Murray sat down with EW to chat about his favorite episodes, working with his daughter, what advice he'd give his younger self, and more.

ENTERTAINMENT WEEKLY: Congratulations on hitting 450 episodes! It's an incredible achievement.

SEAN MURRAY: Thank you, thank you. Yeah, that's pretty wild.

What do you think is the secret to NCIS's longevity?

It's funny, I get asked this question quite a bit, and I always kind of wonder myself. You know, a lot of these procedurals, everyone takes themselves very seriously, it seems. And we have a little more fun. The longer we've been around, the longer people have kind of really gotten to know these characters and like these characters, have become very protective of them.

And I know people love to say this but I actually mean it: we have a blast on set. We really do. We work hard, but we have a lot of fun, and a lot of us spend time with each other outside of the set. We're all very close friends, and I think that that shows.

Do you see this affection for your character when you're out in the world?

To be honest with you, I do. I really do. People just want to say hello. It's great. We really do have some of the best fans.

The show has been through its share of cast changes over the past twenty years. At this point, do you have a routine for welcoming new regulars to the set?

Any time we've introduced a character, we've had the actor there well beforehand on set with us getting to know us. We try to be friendly with everything we do, and that goes with welcoming new cast.

Some people have their guard up because they've come from other sets where it's like, "hit your mark and bark," and it's very hard core. And they come to us and they see that it's friendly and that we encourage the positive dynamics. Everyone seems to just kind of fall in. I've watched everyone do it. I've seen Katrina (Law) do it. I've seen Gary (Cole) do it. I've seen Emily (Wickersham) do it. I've seen everyone kind of just come in and feel that vibe and pick up on it and go with it. And I do think that shows through in the performances. Especially this current ensemble seems to have such great chemistry.

Everything really clicks with the current cast you're working with.

I feel like it really is. And, I mean, I love Gary to death. Gary is fantastic, and I'm having so much fun with him.

Wilmer (Valderrama) is a brother to me. He and I are very, very close and have been since in the seven years I've known him. And Katrina is a blast. I mean, Katrina is so cool. I always joke that Katrina was like built by network television to perform a role perfectly in a show because she's just that good.

Is it different for you working with David McCallum as the last of the season 1 regulars? Does it feel a little different because of the length of your professional relationship?

It's funny, he and I look at each other sometimes and just kind of smile and shake our heads. And we both know what we're saying to each other.

"How did we get here years later?"

Oh, definitely. Absolutely.

Mark Harmon left the show early in season 19, and he shares that last scene of the episode with you. What was it like to be the person filming that?

I had lots of feelings about it because, well, you know, it's Harmon, who is like a mentor to me, and saying goodbye on screen was hard. But at the same time, I felt that if anyone were to do it, McGee is the right one.

Filming that was an unbelievable experience. I will never forget it. It was me, Harmon, Gary, and a splinter group of our crew. We got on a private plane, flew to Alaska for a week, and filmed what I think is some of the best stuff we've ever done.

We were in the water doing the fly fishing, and as I'm saying goodbye to Mark, the whole crew is crying. Danny, one of the grips came up to me afterward and he goes, "I got a bone to pick with you. I'm a grown man. You had me crying, standing in the river."

After Harmon left, your character became the longest-serving member of the team. Did that change your approach to playing McGee?

It's been interesting because when the show started, McGee was the penultimate rookie character. And as the show has progressed, he has progressed. He's definitely a lot more sure of himself than he used to be and capable of doing so much more than he used to be.

Our writers, we've got our guys that have stuck with us for so long, and they know this character just about as well as I do. So it kind of comes naturally with the material, the way the character has grown over the years and I've grown as an actor over the years doing that character.

I think it's kind of cool that I've played one character for 20-plus years. I don't think there's a lot of actors that get the privilege of doing that. I remember talking to the writers early on about this, like, I don't want to be baby Maggie Simpson. I don't want to be the same character every single week and never grow. And they were very into the growth of the character. So it's just been a natural thing, and fun to do.

What's something about you that might surprise your fans: a hobby, a passion in your life? What gets you going when you're not filming?

I'm a real music nerd. I'm constantly on the search for new music. I grew up listening to hip-hop and electronic music. And then, I mean, I'm pretty boring in general. I'm a father. So it's funny, the hobby list gets smaller and smaller as your kids get older and older and there's more to do.

Speaking of kids, you shared the screen with a very special guest star toward the end of season 19. What was it like working with your daughter (Cay Ryan Murray)?

It was so cool on so many levels.

One of the first things we did at the show, we had a picture of my daughter up on the plasma screen in the squad room and we're talking about her being a potential suspect and da da da. And I remember that as soon as we started filming that scene and that picture went up on the plasma screen, my brain went into this sort of, not panic, but it didn't know what to do. I guess I didn't realize how much I kind of compartmentalized work and home. And so all of a sudden, my home life sort of being at work, it flustered me just seeing a picture of her.

That paternal nature came through on the screen so clearly.

That was easy to do, obviously. One of the things I was worried about was the chaos of people on set, everyone coming up, giving you direction, so many different things. I was like, oh, man, I hope she doesn't get overwhelmed, and Cay took it like a champ. She was a total pro. I'm like, I wish I was as cool as she is because she handled it so well. I'm so proud. It's hard to… I'll get choked up.

Oh, that's really lovely. And how nice that you got to share that.

I will always have a piece of film — or digital video — of my daughter and I both doing what we love together on screen. So that's something that will always be there, and I'll always be thankful for that.

Do any other guest stars stand out for you over the course of that 450-episode run?

There was an episode where Lily Tomlin played my grandmother. (2011's "The Penelope Papers," season 9, episode 3.) She came in and that was so fantastic. I had so much fun.

I think of these little moments. Back in season 1, there's an episode called "Dead Man Talking" (episode 19, 2004) where it's kind of the first time you see the foursome, kind of the beginnings of McGee in that episode. You get to see some of his quirks. And you just start to see things click. You start to see the relationship that I had on-screen with Michael Weatherly. The Tony/McGee relationship was a great one.

There was an episode we did where Ziva (Cote de Pablo), Tony, and myself were all captured. (2009's "Truth and Consequences," season 7, episode 1.) And Harmon as Gibbs, the sniper, the military man, the Marine, came in and rescued us. And there was a scene of us in the elevator in the building coming up after all of the crap has happened, and there's total silence. No one says a single word, and everyone is dripping with blood and sweat and looks just like they've had the living hell kicked out of them, and there's just this unspoken thing… I don't quite know how to say it. It's pretty wild though. It's a moment that is one of my favorites.

So knowing what you know now, what advice would you give yourself on your first day of filming NCIS back in 2003?

I wish I could give myself some advice, you know, don't sweat it too much. It's just a TV show. As a young person, I was very much a worrier, so I think in general it would be don't worry so much, whether it be working or just life. It's such a wasted emotion because you worry about things, and the worrying is always going to be the worst of it. It's never as bad as you think it is.

Finally, what's next for NCIS? And what's next for Sean Murray?

When the show eventually ends, I'll want to do something very different, a different type of show and a very different type of character.

I don't want to jinx anything, and knock on wood, but things have been going well for the show and on the show, and we've just been having fun doing it. That carpet can always get yanked out from underneath you and you're out there looking for a job, but I'm so happy where I'm at. My head is just in what we're doing right now.

"Unusual Suspects," the 450th episode of NCIS, airs tonight at 9 p.m. ET/PT on CBS and Paramount+.

This interview has been edited and condensed for length and clarity.

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