'NCIS' Star Mark Harmon 'Backtracking' on Rejoining Show, 'Fickle Attitude' Ticks Off Former Castmates

NCIS star Mark Harmon's departure after 18 seasons devastated viewers and his castmates, who are still dead-set on his return, RadarOnline.com has learned.

Insiders said Harmon might not rejoin the cast after all, despite teasing a potential comeback.

They said his "fickle attitude" has stressed out castmates, who were banking on him to boost the show's ratings. Harmon had been a regular fixture prior to his exit, starring as Special Agent Leroy Jethro Gibbs for 19 seasons before leaving the CBS procedural in 2021.

The spy claimed that almost "everyone wanted him back," but he's been preoccupied with his nonfiction book Ghosts of Honolulu. Harmon's nonfiction book is about the Office of Naval Intelligence, the forerunner to the agency featured on his longtime TV home.

Harmon's latest passion project is slated to hit shelves in November 2023.

"When he was bored, an NCIS return sounded like a good idea. Now he's found something that's interesting, he's less enthused," the insider claimed.

Plus, they told RadarOnline.com that Harmon is hardly hurting for cash, with a reported net worth of $120 million. And that's not all: he's still raking in the cash as an executive producer on the show, even if he never appears in front of the camera again.

The mole said it's a bummer for his ex-colleagues who "wish he would stop getting them excited only to let them down."

RadarOnline.com has reached out to a rep for Harmon for comment.

As for Harmon, he appears to have made peace with his departure. "What has always drawn me here is the character I play and to keep it fresh and to keep it challenging," the Presidio actor said in a special featurette released with the season 19 DVD.

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"Plot-wise, this character has taken the path that it did. I thought it was honest and OK with." Harmon added, "I'm not retired... The character is living in Alaska as far as I know."

Executive producer and showrunner Steven D. Binder also teased a potential return, telling Entertainment Tonight that door may never be fully closed.

Binder said, "So regarding the future of Gibbs, as longtime fans of the show may have noticed over the years… never count Leroy Jethro Gibbs out."