When thinking about NCIS, it’s natural to assume that Mark Harmon (Leroy Jethro Gibbs), Michael Weatherly (Tony DiNozzo), or Pauley Perrette (Abby Sciuto) would hold the record for most episodes on the show. After all, they’re some of the most iconic and long-standing characters in the series’ history.

However, the title of NCIS actor with the most episodes doesn’t belong to any of them. Instead, it goes to David McCallum, who plays Dr. Donald “Ducky” Mallard.

McCallum has been with the show since its inception in 2003, portraying the wise and affable chief medical examiner. Over the years, Ducky became a cornerstone of the series, beloved for his intellect, storytelling, and nurturing presence. While Mark Harmon led the show for nearly two decades, Ducky’s enduring presence and later transition to NCIS historian allowed McCallum to quietly accumulate more episodes than most of his co-stars.

Even as other major characters departed—like Weatherly in season 13 and Perrette in season 15—McCallum stayed, embodying the heart and soul of the team. His role evolved in later seasons to accommodate a reduced schedule, but his legacy remains unshakable.

It’s a testament to McCallum’s dedication and the fans’ love for his character that he holds this record. While Gibbs, DiNozzo, and Abby are household names in NCIS history, Ducky’s enduring presence proves he’s an irreplaceable part of the team.