Mark Harmon Departs 'NCIS' After 18 Seasons: He's 'Always Going to Be a Part of the Show'

Special Agent Leroy Jethro Gibbs is giving up his badge.

Monday's episode of NCIS served as lead star Mark Harmon's final moments on the show as he is exiting the hit CBS series after portraying Gibbs for 18 seasons. During episode four of season 19, Harmon's beloved character — who was nearly killed during the season 18 finale — said goodbye to his job, deciding to stay in Alaska indefinitely after solving a case.

"I'm not going back, Tim," he told Special Agent Timothy McGee (Sean Murray) while fishing. "I'm not going back home."

Gibbs then tells McGee that he "could not have hoped for anyone better" to work with over the past 18 years before the partners hugged, closing out the scene.

Gibbs' goodbye may not be forever, however.

"As an executive producer and dear friend, Mark continues to be an integral part of the fabric of the show. Our north star has always been staying true to our characters, and that truth has always guided the stories we tell and where those characters go," Binder, executive producer, told PEOPLE in a statement. "So regarding the future of Gibbs, as long-time fans of the show may have noticed over the years…never count Leroy Jethro Gibbs out."

"Mark's always been part of the show, Mark's always going to be part of the show," CBS Entertainment President Kelly Kahl told Deadline last month. "In terms of his on-air appearances, we're just going to have to see how it plays out going forward."

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Harmon, 70, has starred on NCIS as Gibbs since the show's premiere in 2003. In April, the long-running series was renewed for season 19 and there was speculation that Harmon wouldn't return at the time.

Speaking to PEOPLE in 2019, Harmon revealed what would ultimately cause him to leave the series after nearly two decades.

"I've always thought if there's ever a time where the writers are walking into the room and going 'I don't know what to do,' then I think we all have to look at each other and call it a day," he said at the time. "But we're not there yet."

Harmon also expressed his gratitude for his long-running spot on the show.

"I've been around long enough to know what this is. That commitment is part of what I signed up for; I know when this show ends that's it — there won't be anything else like this for me," he added.

The action drama's current cast includes Murray, Brian Dietzen, Diona Reasonover, Wilmer Valderrama, Rocky Carroll and David McCallum.

NCIS airs on CBS Mondays at 9 p.m. ET. Fans can rewatch past seasons on the Paramount+ streaming service.