Dr. Donald “Ducky” Mallard, portrayed by David McCallum, was the last original cast member on “NCIS” until his recent minimal appearances since Season 19. Mark Harmon, another original cast member, exited in Season 19, but Sasha Alexander was the first to leave, departing after 49 episodes as Special Agent Caitlin “Kate” Todd. Alexander, who debuted in the 2003 pilot “Yankee White,” played Kate, a former Secret Service agent who joined Gibbs’ team, quickly becoming a beloved character. Her conservative demeanor contrasted humorously with Tony DiNozzo’s, creating a dynamic team along with Timothy McGee.
However, Alexander chose to leave due to the demanding production schedule, a common reason among actors, leading to Kate’s dramatic on-screen death in Season 2. Despite her departure, Alexander has no regrets, as it allowed her to pursue a fulfilling personal and professional life. Over the years, NCIS has experienced significant cast turnover, with notable exits including Cote de Pablo’s Ziva David in Season 11. Yet, actors often return for special episodes, as Alexander did for the show’s 200th episode in Season 9, demonstrating a lasting connection with the series.