Why NCIS Creator Don Bellisario Didn't Want To Cast Mark Harmon As Gibbs
"NCIS" creator Don Bellisario initially had several other actors in mind for Leroy Jethro Gibbs, and wasn't sure if Mark Harmon was the right fit for the fan-favorite character. However, after managing to prove Bellisario wrong, Harmon became synonymous with the military police procedural franchise.
"NCIS" premiered on CBS in 2003, arriving eight years after Bellisario's fellow CBS hit "JAG." Several core "NCIS" characters were introduced on "JAG," including Harmon's Gibbs.
There are conflicting reports regarding what Bellisario knew about Harmon before the "NCIS" casting process. A 2005 USA Today article indicates that Bellisario was familiar with Harmon's prior roles, whereas casting director Susan Bluestein told The Hollywood Reporter in 2023 that Bellisario "hadn't seen a lot of Mark's work."
Originally, Scott Glenn was a top pick for Gibbs. Harrison Ford was a dream casting choice for Bellisario, but he knew it was a long shot. According to casting director Susan Bluestein, Charlie Sheen, Alec Baldwin, Clive Owen, Val Kilmer, Patrick Swayze, and Kevin Bacon were also among the explored possibilities, but no formal offers were made.
Harmon has another TV role to thank for him landing the role of Gibbs
Had Mark Harmon not played Secret Service Special Agent Simon Donovan in a four-episode arc on "The West Wing" in 2002, he may not have gotten his most notable role to date on "NCIS." Seeing a tape of the actor's performance on the political drama ultimately shifted Bellisario's initial beliefs about Harmon.
"I said, 'Oh, my God, he's Gibbs," Bellisario told USA Today. "He had matured. He's good-looking in a totally different way than he was as a young guy."
Harmon was a series regular on "NCIS" before exiting early into Season 19's run in 2021. In 2026, he reprised his role on Season 3 of the prequel series "NCIS: Origins." He had already been involved as both an executive producer and series narrator, voicing an older version of Gibbs.
Bellisario and Harmon had an apparent falling out before Bellisario left "NCIS" after Season 4 wrapped production. At the time, TV Guide quoted unnamed sources who said Harmon was frustrated by Bellisario micromanaging "everything" and his "chaotic management style."