NCIS: The Truth About Mark Harmon & Michael Weatherly's Relationship

Michael Weatherly enjoyed a home on CBS for almost 20 years. The actor was an original cast member on "NCIS" where he starred as Anthony DiNozzo Jr., the charismatic senior field agent from the show's Major Case Response Team. And while DiNozzo was a beloved character during his 13 seasons with the series, Weatherly didn't always understand how to work with Mark Harmon, who played Agent Leroy Jethro Gibbs until his Season 19 departure.

In a 2007 interview with The Futon Critic, Weatherly said that Harmon "was confused by my presence right from the get-go." He explained that he booked "NCIS" after acting on a series of failed Fox shows and that his attitude going into shooting the pilot was to try to have as much fun as possible. This professional approach didn't exactly jibe with Harmon's mentality, and Weatherly claims the two were polar opposites. "I was Antarctica, he was the North Pole, and we were just looking down there going, 'What is up with your polarity? What's going on? The water goes down the drain the other way for me," he shared.

Weatherly remained on "NCIS" until 2015 when he left to lead his own CBS show, "Bull," which premiered in 2016 and ran until 2022. Industry reporting suggests Weatherly is interested in returning to his old series now that "Bull" is over — but behind the scenes, people are doubtful Weatherly will actually come back.

Michael Weatherly said his six-year run as the lead actor on the CBS show "Bull" gave him perspective on his former "NCIS" cast member, Mark Harmon. The show, which is inspired by the early career of Dr. Phil McGraw, stars Weatherly as Dr. Jason Bull, a psychologist and trial consultant. In an interview with USA Today, Weatherly admitted, "It's been very illuminating and given me a great deal of insight and regard for what Mark Harmon was doing all those years (on 'NCIS'), when I was like, 'How come he doesn't have as much fun as the rest of us?'"

One thing Harmon did enjoy about his interactions with Weatherly's character was slapping him. Now referred to as the "Gibbs head slap," the gesture started as an improvised moment between Agent Gibbs and Agent DiNozzo during a scene. In an interview with Premiere (via Showbiz CheatSheet), a French news outlet, Harmon explained that during filming, Weatherly, "was doing what he does, which is sometimes stay on script and sometimes not. I just reached over and smacked him. I tried to put him back online. It was an instinct."

Harmon said the producers integrated the slap into the show, where it became a regular occurrence between the two characters. "Every episode I was smacking him — maybe too much," the actor claimed.

Now that "Bull" is over, fans think Michael Weatherly is interested in revisiting his old stomping grounds. In July 2023, he posted a picture on X (formerly Twitter) of himself receiving the Gibbs slap from a friend. A few days later, he wrote, "I feel like things are starting to happen. Things that will be very exciting," causing fans to speculate that he was teasing a return to "NCIS." 

In 2022, "NCIS" showrunner Steven D. Binder told TVLine he was open Weatherly returning, but it seemed doubtful it would happen. He said, "When [Michael] left "NCIS," he said to me, 'I am never going to do network television again.' He had just had some kids, and the hours are so long... but then this "Bull" thing landed in his lap, and again he was working like a fiend."

As for Mark Harmon, he left the show in 2021, and his departure was explained by Gibbs moving to Alaska. But while his character no longer appears on-screen, Harmon remains involved behind the scenes. "NCIS" star Diona Reasonover, who portrays Kasie Hinds, told Entertainment Tonight that as an executive producer, Harmon is very involved with the show and still comes to set.

It's too soon to tell if either of these former stars will return to "NCIS" in a performative capacity. But if Harmon and Weatherly end up acting opposite each other again, it would seem likely that another "Gibbs head slap" could be in Weatherly's future.