For years, NCIS fans watched Mark Harmon bring Leroy Jethro Gibbs to life. But some viewers didn’t realize that one familiar face from Gibbs’ past was actually much closer to Mark than they thought.
Sean Harmon, Mark’s real-life son, portrayed the younger Gibbs in several episodes of NCIS. He eventually stepped away from playing the character, but he didn’t walk away from the NCIS world. Sean became an executive producer on NCIS: Origins, working behind the scenes alongside his father.
And their connection continues beyond television. Sean and his wife welcomed their first child in 2025, making Mark a grandfather for the first time.
So despite dramatic rumors that can surround famous families, there’s no credible evidence that Sean stopped calling Mark “Dad” or that the two are estranged.
Their real story may be simpler — a father and son who found their own ways to carry the Gibbs legacy together.
