With nearly 50 years in showbiz under his belt, Mark Harmon is one of the most successful stars in Hollywood.
He also happens to be one of the most private. "It's not even a choice," the NCIS actor has said of remaining firmly under the radar with his wife of 33 years, actress Pam Dawber. "It's who we are. We stay home. A lot. And I'm not a Twitter guy or a Facebook guy."
But a source tells OK! the beloved star and father of two is finally ready to open up about his little-known world like never before. "Mark's decided to share some of his best-kept secrets on marriage, fatherhood and his incredible career," says the insider. The 69-year-old is planning to tell all in an upcoming memoir, in which he'll touch on everything from on-set drama to personal tragedy.
"Mark's had a ton of downtime lately, so he's been writing a lot," the source reveals. "He wants to feel more connected to his fans and shed some light on who he really is."
Harmon has plenty to say about his resilient relationship with Dawber. It was love at first sight when the duo met at a party in 1986, and they wed a year later. Dawber, 68, was super-famous at the time, thanks to starring roles on TV's Mork & Mindy and My Sister Sam, but she decided to put acting on the back burner when she and Harmon welcomed their two children, Sean, 32, and Ty, 28.
"Pam abandoned her successful career to focus on raising their sons," says the source. "The boys are now both actors and doing great things, so she feels it was a job well done."
As a couple, Harmon and Dawber always had their priorities in order. "Their secret is they put their family first above all else, including work," says the source. They still prefer spending time together at home over attending glitzy red carpet events.
"They're both homebodies," says the source. "Mark prefers to stay out of the spotlight and avoids industry parties, and while Pam still takes the odd acting job here and there, she loves tending the garden, cooking and making a beautiful home for her family."
But it hasn't always been smooth sailing. Shortly after their marriage, the couple hit a rough patch when Harmon got embroiled in a custody battle over his then 13-year-old nephew. The star's older sister, Kristin, had gotten involved with drugs, and Harmon and Dawber went to court so the son could live with them. "They felt Kristin was setting a bad example with her ongoing substance abuse issues," explains the source. "But when the defense team threatened to put Pam on the stand and quiz her about her own past experience with drugs, Mark felt forced to settle the suit."
It was a strain on his relationship with Dawber, but Harmon and his sister eventually buried the hatchet before she passed away in 2018. "Mark's a tough guy," says the source, "but he's loyal and doesn't hold grudges."
The actress left the show in 2018 and later tweeted she was "terrified" of the actor. The two reportedly stopped speaking when Harmon's pit bull mix attacked someone on set in 2016. "Pauley felt the dog was ferocious," shares the source, "and after a crew member had been bit, she thought Mark should not be allowed to bring it to the set."
Perrette blamed Harmon when she was let go from the series, claiming she had "nightmares" about him. The actor remained silent on the controversy, but now, "he wants to finally address what really happened," the source shares. "He says he had nothing to do with it, and he wishes her the best."
Despite reports he may be retiring soon, the source tells OK! Harmon will be back for season 18 of NCIS and has no plans of ending his 17-year run in the near future. "Mark's happy to say he's returning as Leroy Jethro Gibbs, and he'll stay as long as they want them."
In the meantime, he's enjoying his low-key life with Dawber at home in Los Angeles. "Mark may be worth well over $100 million, but he's never been a big spender," explains the source, adding that he prefers fixing things around the house himself rather than hiring a handyman. "Mark spends afternoons doing carpentry, working on his cars or cooking with Pam. Those are the moments he cherishes."
The source says Harmon hopes fans will soon see a different side of him.
"Mark's changed over the years. He's mellowed with age, and he's not as buttoned-up as he seems," adds the source. "He might come off as standoffish, but people will be shocked to know he has a great sense of humor and is actually a pretty easygoing guy."