NCIS has been on our screens for almost two decades, so it's no surprise that the show has featured cameos from some major stars over the years.
One Hollywood actor you may have forgotten appeared in the long-running CBS drama is none other than Zac Efron!
The 17 Again star played the role of teenager Daniel Austin, who is taken to the NCIS headquarters for questioning after he and his friend are caught with a phone that was previously used by a kidnapping victim calling for help.
Agents Tony DiNozzo and Ziva David soon realize that Daniel and his friend had nothing to do with the crime and were sold the phone by another boy.
The synopsis for the episode, titled 'Deception', reads: "A woman Naval Officer becomes abducted, and she calls NCIS on her cellphone; Gibbs and the gang investigate.
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"She's involved with both a movement of nuclear-fuel rods and an anti-pervert group. The team find her, and they solve the case."
Zac's cameo aired on January 17, 2006 – just three days before the premiere of High School Musical. Zac played Troy Bolton in the movie, which would become his breakout role, as well as a pop culture phenomenon.
Zac isn't the only major star to have appeared on the show, however. Former FLOTUS Michelle Obama, Jamie Lee Curtis and Lily Tomlin have all appeared in past episodes.
One actor fans are hoping will make an appearance in the upcoming season 20 finale is former star, Mark Harmon.
Mark stepped away from the drama in 2021 after fronting the show for 18 seasons, with a minimal role in the 19th series.
Will Mark Harmon return to NCIS?
While Mark has yet to comment on whether he would return to the show, his friend and co-star Rocky Carroll addressed the possibility in an interview with TV Insider. "We might see Gibbs again," he said. "I think as long as this show stays on the air, there will always be a little bit of a tease that we might see Gibbs again.
"Gibbs is the moral compass. He's the moral compass that we all wish we had," he added.
The show's cast and crew have also made it clear that they'd love to see Mark reprise his role. Sean Murray, who plays Agent Timothy McGee, told Parade last year: "I really, truly believe that the Gibbs could pop up somewhere. I really believe that there's a possibility of that happening."
What's more, following Mark's departure, showrunner Steven D. Binder released a statement that heavily suggested that the Leroy Gibbs actor could make a comeback in the future. "As an executive producer and dear friend, Mark continues to be an integral part of the fabric of the show," he said. "Our north star has always been staying true to our characters, and that truth has always guided the stories we tell and where those characters go.
"So regarding the future of Gibbs, as long-time fans of the show may have noticed over the years… never count Leroy Jethro Gibbs out."
He later told TV Insider: "I don't see how we don't see him one more time at one point."
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