NCIS is indeed one of television's longest-running crime dramas that has garnered a mass audience and has successfully built a huge fanbase over the years. This has been possible because of its iconic cast members, who have kept shifting and changing throughout seasons but still have been able to carve a mark in their fans' hearts.
Over the years, several of its beloved cast members have left the show, making their departure emotionally difficult for long-time viewers and NCIS fans. Here is the list of 5 characters who have left the CBS procedural drama and the reasons behind these exits.
Here are the 5 most prominent NCIS stars who quit the show

Sasha Alexander as Caitlin "Kate" Todd
Sasha's character of Special Agent Caitlin appeared in seasons 1 and 2 of NCIS, and then her fans were surprised by her brutal exit. She was assassinated by Ari with a single bullet to the head, marking the exit of the original cast member.
Neither creativity nor logistics was the reason behind the exit of this actress. Sasha's exit was a result of the escalating workload of network television. In her 2012 interview with TV Guide, she explained how the scheduling of the show was overwhelming.
“People don't realize… you make 24 episodes a year — that’s 10½ months a year, 17 hours a day. It’s hardcore.”
The actress tried her best to keep up with that pace but realised that she couldn’t sustain it long-term. Therefore, leaving NCIS gave her a healthier work-life balance and a chance to pursue more creative projects.

Michael Weatherly as Agent Anthony DiNozzo
Michael's character in NCIS added comic relief to the otherwise crime drama. One of the show's charismatic characters, who appeared for 13 long seasons, eventually exited the show. Reports suggest that his decision to leave the show was not sudden but took almost two and a half years.
The actor mentioned that it was Cote de Pablo whose exit impacted him, as their chemistry was a huge part he enjoyed about being in the show. After Ziva left in Season 11, he felt the heart of Tony's storyline was gone, too.
NCIS executed the exit of the character by showing him leaving to take care of the daughter he has with Ziva.
Cote de Pablo as special agent Ziva David
Pablo played a fan-favourite character as Special Agent Ziva David, who was introduced in season 3 and stayed for eight long years in the show. Finally, in 2013, she left the show because she was not happy with where her character was leading.
But in 2016, she finally said,
"Look, I love this character! I worked for eight years crafting Ziva and when I felt like the character wasn't being treated with the respect she deserved."
She added that the show wanted to send Ziva back to Israel and transform her arc to give it darker undertones. She claimed this compelled her to exit the show while she personally wanted to continue.

Mark Harmon as Leroy Jethro Gibbs
Gibbs' exit came as a great, shocking reveal for fans who had been viewing this show for years. Viewers were connected with this leader and emotional anchor of NCIS. His character had become the face of the show. In the 2021 Season 19, Gibbs' storyline concluded with him choosing to stay in Alaska, marking Mark Harmon's departure from the CBS drama.
Moreover, what made fans restless was Harmon's silence about his character's exit. He didn't reveal anything for about a year about the reasons behind it. Later, in one of his interviews, he stated that the scope for getting to do better and fresh things in NCIS was diminishing. Also, he didn't feel there were new story directions left for Gibbs.
Pauley Perrette as Abby Sciuto
Pauley Perrette portrayed Abby Sciuto, the fan-favourite forensic scientist who was NCIS's most popular character for more than 15 years. In the storyline, Abby survives the assassination attempt but decides to resign from NCIS, dedicating her life to a charitable project.
Now, the real reason the actress exited was some behind-the-scenes tension with Mark Harmon. Several reports mention that when Harmon's dog bit a crew member, the incident sparked tension between Pauley and him following multiple disagreements.
This was the list of cast members who left the CBS drama over the years but remain in the hearts of their fans.