Who is Mark Harmon? Everything to know as the NCIS legend returns for the upcoming crossover event

Mark Harmon, who played the original Leroy Jethro Gibbs on NCIS for 19 seasons, retired from his onscreen character in 2021. While Harmon Gibbs relocated to Alaska, he narrates the story of his younger days in NCIS: Origins, which is in its second season currently. 
While the spinoff is presenting the making of Agent Gibbs, NCIS is airing its season 23. The upcoming episodes for November 11, 2025, will see a crossover event that is slated to bring back Mark Harmon as Gibbs.

Meanwhile, NCIS season 23 premiered on October 14, 2025. The season premiered with a two-part storyline that revealed Parker’s war against Carla. The third episode played out Torres’s predicament as he suffered a setback in trying to save his family friend.

NCIS season 23 episode 4 found the FBI collaborating with Parker. On the other hand, NCIS: Origins season 2 started with Lala’s return after a long recuperation following her car crash in the previous season. While Gibbs was shown dating Diane, which hurt Lala, the latter decided to set a good example for Gibbs to follow. 

Moreover, Mike Franks reunited with his long-estranged brother, Mason, as the siblings looked for ways to save their family home. 

A glimpse at NCIS star Mark Harmon

Burbank-born Thomas Mark Harmon started his career as a merchandising director for businesses before turning towards acting. His early roles had him portraying medical personnel and law enforcers. One of his first television projects was Ozzie’s Girls. 

Some of the other television projects that involved Harmon are Chicago Hope, Reasonable Doubts, St. Elsewhere, Flamingo Road, 240-Robert, Sam, Centennial, Moonlighting, Charlie Grace, The West Wing and many more.

The talented actor has featured in numerous movies, including Freaky Friday, Freakier Friday, Weather Girl, Crossfire Trail, The Last Supper, The Amatti Girls, Till There Was You, Summer School, Comes a Horseman and more. Harmon has received more than fourteen award nominations. 

In his personal life, Mark Harmon was the son of a football-broadcaster father and a model-actor mother. He is married to actor Pam Dawber. Harmon was a football player in his high school and later. He received the All-Round Excellence award from the National Football Foundation and continues to be involved with football and is known to be a philanthropist.

Mark Harmon’s current arc in NCIS

As mentioned before, Mark Harmon embodied Agent Gibbs for 19 seasons before the character walked away from his job. He has stayed in Alaska in solitude for four years. Gibbs’ musings present his origin story in the form of a spinoff to the main series.

However, Harmon stayed connected to the franchise as one of the executive producers and narrated his backstory in Origins. The original and the spinoff are set to present a crossover that will feature Mark Harmon onscreen.

While the storyline for the crossover has been kept under wraps, the spoilers suggest that the NIS team of the 90s will come across a Navy-connected crime that baffles Franks’ team. At the same time, the present NCIS season 23 storyline reopens the same unsolved crime from the 1990s. This hints at the connection where Mark Harmon’s Gibbs may return to give his insights into a crime done decades ago in Pendleton.

Tune in to CBS on November 11, 2025, to catch the crossover event featuring Mark Harmon starting with NCIS: Origins at 8 pm ET/PT, followed by NCIS at 9 pm ET/PT.