Former UCLA quarterback and NCIS star Mark Harmon is causing concern among friends and fans alike. Once a robust 6-foot-1 college football star, the 65-year-old actor, known for his role as Special Agent Jethro Gibbs, is reportedly struggling with his health. According to a top weight loss expert, Harmon has shed at least 20 pounds, dropping to 157 pounds, and appears frail and reclusive.
“Mark seems to have wasted away,” says a source close to him. “He spends most of his time indoors and appears to have much less energy.”
Concerned friends note that the actor, who was once very active, is now rarely seen outside his Los Angeles home. He was recently spotted struggling with a delivery box and looking a far cry from his on-screen persona. “He didn’t look well and hadn’t been seen publicly for over 250 days,” shares one source.
Despite his rep denying any health issues, insiders say Harmon is haunted by his family history. His father, Tom Harmon – a legendary college football star and Heisman Trophy winner – died suddenly of a heart attack in 1990. “Losing his father so suddenly has left a lasting impact on Mark,” says a friend. “I fear he thinks he’s destined for the same fate.”

Dr. Stuart Fischer, author of The Park Avenue Diet, notes that while genetics plays a role in heart disease, factors like obesity and diabetes are more significant. Nonetheless, he advises Harmon to undergo a stress test, especially considering his family history.
The sudden death of NCIS creator Gary Glasberg in 2016, at just 50, reportedly shook Harmon deeply. “It came out of nowhere,” says a source. “Mark began discussing retirement with his wife Pam Dawber not long after.”

Sources say Harmon, father of Sean and Ty, may step away from NCIS after its 15th season. Fans on social media are encouraging him to take a break, noting his noticeable weight loss and apparent frailty.
“Mark needs to rest and take care of himself before he ends up like his father,” an insider warns.