NCIS: Mark Harmon's role almost went to this A-lister

In the competitive world of television, while many shows fizzle out after a few seasons, others become legends in their own right. 

NCIS falls squarely into the latter category. Beginning in 2003 as a promising backdoor pilot on CBS' JAG, few could have predicted its unprecedented success.

Under the skilled hands of co-creators Donald P. Bellisario, renowned for classics like Magnum, P.I. and Quantum Leap, and Don McGill, known for hits like Numbers and CSI, NCIS introduced audiences to the complex world of D.C.’s Naval Criminal Investigative Service. 

Led by Leroy Jethro Gibbs, portrayed by Mark Harmon, the series quickly amassed a loyal fan base. 

With a dynamic ensemble cast, including the likes of Michael Weatherly, Sasha Alexander, Pauley Perrette, and David McCallum, NCIS solidified its position as CBS's crown jewel, boasting the title of the network's No. 1 drama for five consecutive years. 

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Its massive appeal led to four spin-offs, with NCIS: Sydney being the latest addition, set to premiere this fall.

To commemorate the show’s 20th anniversary since its 2003 premiere, The Hollywood Reporter organized a sit-down with the brilliant minds behind this behemoth of a show. 

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This included not only Bellisario and McGill but also industry stalwarts like executive producers Charles Floyd Johnson and Mark Horowitz, along with an array of influential names from CBS. 

The illuminating discussion touched upon the many elements that contributed to the show's longevity, ranging from casting decisions and behind-the-scenes transitions to its evolving character arcs and the secrets to keeping fans hooked.

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One of the most intriguing aspects revealed was the selection process for the character of Leroy Jethro Gibbs. 

The choice was far from straightforward. The creative team considered a veritable "who's who" of A-listers for the lead role. 

Harrison Ford's name was among those tossed into the ring, as Charles Floyd Johnson reminisced: "I know Harrison Ford was a name that everybody thought about for Gibbs because he was so perfect." 

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Yet, as Susan Bluestein, the NCIS casting director, elaborated, the initial brainstorming also brought forth other prominent names like Alec Baldwin, Chris Cooper, Clive Owen, Kevin Bacon, and even Charlie Sheen, among others. Don McGill provided further insight, highlighting Andrew McCarthy's brief stint in consideration for Gibbs.

However, the course of the show's history changed when Bluestein brought up Mark Harmon. To many, Harmon was a heavyweight, and the general sentiment echoed Peter Golden's thoughts: “What about Mark Harmon? We'll make an offer to Mark Harmon, and when we don't get him, let's go through the list of who else we could get." 

To everyone's delight and perhaps surprise, Harmon's meeting with Bellisario was a success. They had found their Gibbs.

NCIS's ascent to global acclaim is a testament to the combined creative prowess of its makers, casting decisions, and the actors' performances. 

But as fans of the show will attest, while other characters have made their mark, there is only one Leroy Jethro Gibbs. And it's hard to imagine anyone but Mark Harmon at the helm.