After 18 seasons, it may be finally time to say goodbye to everyone's favorite "NCIS" cast member, Mark Harmon.

Not only is he an actor since 2003, but he also serves as the show's executive producer.

After more than 400 episodes aired, rumors circulated that perhaps Harmon is ready to put his gun and badge down.

Here are some of the clues that point that Leroy Jethro Gibbs will be leaving the show.

The 'Changes' in the Entire NCIS Universe

"NCIS" not only has one main show, but it also introduced numerous spin-offs, including "NCIS: Los Angeles" in 2009 and "NCIS: New Orleans" in 2013.

All of these three series have generated massive ratings for CBS.

It also provided great syndicated deals in more than 200 countries, making "NCIS" one of the network's most valuable IPs.

Unfortunately, last month, CBS announced that they were canceling "NCIS: New Orleans" after only seven seasons.

In a report by the Hollywood Reporter, a new spin-off is reportedly also in the works. However, Mark Harmon isn't reported to be attached to "NCIS: Hawaii."

Mark Harmon's End of Contract

In the past couple of years, Mark Harmon renegotiated his terms several times.

According to Cinema Blend, the last time his contract was up for renewal was in 2013.

In the end, he renewed his contract despite claiming he was done with the show. It turns out that Michael Weatherly, another OG "NCIS" cast member who exited the show after 13 seasons.

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Now that his contract is up for renewal once again, it's only stirring rumors that Mark Harmon is finally done with the show.

Will There Be an 'NCIS' Season 19?

Even though Mark Harmon is reportedly ready to quit, it doesn't mean he will be canceling "NCIS."

According to several insiders, they claimed that when Harmon found out CBS would cancel the show once he left, he began to meet with executives asking for a possible return on the 19th season.

But in those reports, Harmon would reportedly not be a full-time cast member but would only return to a few episodes once CBS commits to renewing "NCIS" after season 18.

Gibbs' Dark Storyline

Additionally, another clue that would provide Harmon is leaving after this season is his dark storyline.

In the 10th episode of this current season, Gibbs was taken away in handcuffs and was suspended "indefinitely" after using force during an interrogation.

Without his character being the leader of the pack, everything seems to be up in the air, and it's unclear if Gibbs will return on the show.

READ MORE: 'NCIS' Season 18: Special Episodes to Be Aired Amid Mark Harmon Leaving the Show Rumors