When NCIS premiered on September 23, 2003, few people could have imagined that the series would become one of the longest-running television dramas in American history.

It began as a spin-off of JAG, following investigators from the Naval Criminal Investigative Service as they handled murders, espionage, terrorism, disappearances and other crimes connected to the United States Navy and Marine Corps.

But the investigations were only part of the reason audiences stayed.

The real heart of NCIS was its characters.

Leroy Jethro Gibbs was the intimidating former Marine who rarely needed to raise his voice.

Anthony DiNozzo was the wisecracking agent who could turn almost any situation into a movie reference.

Caitlin Todd was the former Secret Service agent trying to understand the strange family she had joined.

Abby Sciuto looked like she belonged in a Gothic nightclub but behaved like one of the warmest people in the building.

And Dr. Donald “Ducky” Mallard spoke to the dead as though they were old friends waiting to tell him one final story.

More than two decades later, the cast looks dramatically different.

Some actors left voluntarily.

Some characters were killed without warning.

Others disappeared for years before making surprising returns.

Several performers retired or moved into entirely different chapters of their lives.

And some members of the enormous NCIS family tragically died.

No loss is more closely connected to the original cast than David McCallum.

McCallum was already a television legend decades before he became Ducky.

Born September 19, 1933, in Glasgow, Scotland, he achieved international fame during the 1960s as Illya Kuryakin in The Man from U.N.C.L.E.

For many actors, one role that famous would have defined an entire career.

McCallum somehow found another.

He was nearly 70 when NCIS began.

Yet Ducky never seemed like a character who had been inserted merely to provide an older voice of wisdom.

He was essential.

Ducky possessed extraordinary medical knowledge, but what made him memorable was his humanity.

He talked to bodies during autopsies.

To outsiders, it could seem eccentric.

To Ducky, the dead were still people.

Their lives mattered.

Their stories mattered.

Finding out what happened to them was an act of respect.

His long stories sometimes tested Gibbs’ patience, but audiences came to love them.

Ducky could begin discussing a murder victim and somehow end up recalling something that happened decades earlier on another continent.

Beneath the humor was enormous experience.

McCallum remained with NCIS as the years passed.

Eventually, the series acknowledged his age.

Ducky stepped away from his full-time responsibilities as chief medical examiner and became the NCIS historian.

Jimmy Palmer assumed greater responsibility in the morgue.

It felt natural.

The teacher was allowing the student to take over.

Then reality delivered the goodbye nobody wanted.

David McCallum died on September 25, 2023, only days after his 90th birthday.

He had been part of NCIS for twenty years.

The series later honored both Ducky and McCallum.

For longtime viewers, the loss was different from an ordinary character departure.

Ducky could not return for a surprise episode.

There would be no secret explanation revealing that he had been living somewhere else.

The actor himself was gone.

Yet old episodes preserve him exactly as audiences remember him.

Ducky walks into the morgue.

He puts on his glasses.

He begins an autopsy.

Then he starts telling another story.

Mark Harmon became the other great foundation of NCIS.

Born September 2, 1951, Harmon was already an established television star before becoming Leroy Jethro Gibbs.

His father, Tom Harmon, had been a celebrated football player and broadcaster.

Mark Harmon also played college football at UCLA before eventually choosing acting.

His pre-NCIS career included major roles in St. Elsewhere, Chicago Hope and numerous television movies and films.

Then Gibbs changed everything.

Gibbs was difficult to understand at first.

He could be brutally direct.

He disliked unnecessary technology.

He enforced strange rules that his agents gradually memorized.

He communicated through looks, silence and the occasional slap to the back of someone’s head.

But the severity concealed enormous grief.

Years earlier, Gibbs’ first wife, Shannon, and their young daughter, Kelly, had been murdered.

That tragedy explained much of his emotional isolation.

NCIS gradually became his replacement family.

Tony was the reckless younger agent he repeatedly disciplined but deeply trusted.

McGee became the inexperienced recruit Gibbs watched grow into a leader.

Abby occupied an almost daughter-like place in his life.

Ziva eventually developed an intensely paternal relationship with him.

Ducky was one of the few people who understood pieces of Gibbs’ past.

For eighteen seasons, Harmon was the center of the series.

Then, in 2021, Gibbs finally walked away.

The character traveled to Alaska and discovered something he had been unable to find for years.

Peace.

Gibbs was not killed.

That distinction mattered.

His story could continue beyond the walls of NCIS.

Harmon subsequently remained connected with the franchise through NCIS: Origins, which explores the younger Gibbs.

By 2026, Mark Harmon had become one of the elder statesmen of the entire NCIS universe.

Watching the earliest episodes now creates an extraordinary contrast.

The supposedly old, experienced Gibbs looks young compared with the man Harmon eventually became.

Then there is Michael Weatherly.

Anthony DiNozzo could easily have been unbearable.

He teased everyone.

He flirted constantly.

He quoted movies during investigations.

He behaved immaturely.

He seemed fascinated by his own charm.

But Weatherly gradually revealed that much of Tony’s behavior was armor.

When a situation became serious, DiNozzo became serious.

He was an excellent investigator.

He could lead.

He was fiercely loyal.

And his relationship with Gibbs gradually began to resemble that of a son seeking approval from a demanding father.

Weatherly was born July 8, 1968.

He remained on NCIS for thirteen seasons.

During those years, Tony experienced one of the show’s most important relationships.

Ziva David.

The chemistry between Tony and Ziva became impossible to ignore.

They irritated each other.

They competed.

They flirted.

They protected each other.

For years, the show refused to give viewers a simple romantic resolution.

Then Ziva left.

Later, Tony learned something that completely changed his life.

He and Ziva had a daughter.

Tali.

That revelation became central to Tony’s departure from NCIS.

He left the agency to become the father his daughter needed.

Weatherly then moved directly into another major television role, starring as Dr. Jason Bull in Bull.

But audiences never stopped associating him with DiNozzo.

Tony had become too important to the franchise.

And his relationship with Ziva was still unfinished.

Cote de Pablo’s arrival as Ziva David had originally followed one of the most shocking moments in NCIS history.

Before Ziva, there was Kate Todd.

Sasha Alexander played Caitlin Todd.

Kate began as a Secret Service agent.

After leaving that job, she joined Gibbs’ team.

Her relationship with Tony became one of the funniest parts of the early series.

They behaved like siblings.

They insulted each other.

They competed.

They invaded each other’s personal space.

And underneath everything, they cared deeply about one another.

Then came the Season 2 finale.

Kate survived a dangerous confrontation.

For a moment, everyone appeared safe.

Then she was shot and killed by Ari Haswari.

The moment was devastating because it happened so suddenly.

There was no long hospital sequence.

No sentimental farewell.

Kate was alive.

Seconds later, she was gone.

Sasha Alexander herself had chosen to leave the demanding production schedule.

Unlike Kate, her career continued successfully.

Alexander eventually became Dr. Maura Isles on Rizzoli & Isles, another major television success.

She also expanded into directing.

But Kate’s death permanently changed NCIS.

The characters mourned her.

Tony carried the loss.

Gibbs carried it.

Abby carried it.

And the woman eventually joining the team arrived with a disturbing connection to Kate’s killer.

Ziva David was Ari Haswari’s half-sister.

Cote de Pablo was born November 12, 1979, in Santiago, Chile.

Ziva initially entered the series as a Mossad officer.

Gibbs had every reason not to trust her.

Then Ziva killed Ari to save Gibbs.

That decision changed everything.

Eventually, she joined NCIS.

Ziva was physically formidable and highly trained.

She could speak multiple languages.

She understood espionage and undercover work.

But the longer audiences knew her, the more complicated she became.

Her toughness concealed enormous emotional damage.

Her father, Eli David, was a powerful figure within Mossad.

Their relationship was difficult and sometimes painful.

Ziva had grown up in a world where loyalty and family could become weapons.

NCIS gave her another kind of family.

Gibbs became a paternal figure.

McGee became a trusted colleague.

Abby eventually accepted her.

And Tony became something much more difficult to define.

Cote de Pablo left as a regular cast member in 2013.

For many fans, her departure was heartbreaking.

Then NCIS made audiences believe Ziva had died.

Tony learned that Ziva had given birth to their daughter, Tali.

He left to raise her.

But years later came the revelation few viewers expected.

Ziva had survived.

De Pablo returned to the series, reopening a story audiences thought had ended permanently.

The Tony-and-Ziva relationship ultimately became large enough to extend beyond the original series.

Their story demonstrated something NCIS repeatedly learned during its extraordinary run.

A goodbye did not always mean forever.

Pauley Perrette’s goodbye was different.

Perrette played Abby Sciuto.

Abby became one of the most instantly recognizable forensic scientists in television history.

Black clothing.

Pigtails.

Tattoos.

Platform boots.

A Gothic aesthetic.

And enormous quantities of Caf-Pow.

Yet Abby’s appearance deliberately contradicted her personality.

She was affectionate.

Excitable.

Optimistic.

Intensely loyal.

She could become emotionally attached to victims she had never met.

She hugged colleagues.

She treated forensic breakthroughs like celebrations.

And she loved Gibbs.

Their relationship became one of the emotional anchors of the series.

Gibbs rarely expressed affection openly.

With Abby, he did not need to.

A look or kiss on the cheek communicated everything.

Perrette remained on NCIS for fifteen seasons before leaving in 2018.

Her departure became complicated by reports of serious behind-the-scenes tensions.

Afterward, she made clear publicly that she did not intend to return to the series.

Perrette later starred in the sitcom Broke.

Then she stepped away from acting.

She subsequently revealed that she had suffered a serious stroke in 2021.

Fortunately, she survived.

By 2026, Pauley Perrette remains retired from acting.

For viewers who remember Abby as an almost impossibly energetic presence, the contrast between those early episodes and the passage of real time can be emotional.

Then there is Sean Murray.

Murray’s transformation may be the most remarkable of all.

Timothy McGee first appeared during the first season.

He was not originally the confident senior agent audiences know today.

He was nervous.

Inexperienced.

Technologically gifted.

And frequently tormented by Tony.

DiNozzo gave him the nickname that followed him everywhere.

“Probie.”

McGee seemed permanently destined to be the younger member of the team.

But television characters age when a series lasts more than two decades.

McGee gradually became an experienced investigator.

He survived shootings.

Kidnappings.

Explosions.

Personal crises.

He married Delilah Fielding.

He became a father.

He gained confidence.

Eventually, the nervous probationary agent became one of the institutional veterans of NCIS.

The transformation becomes almost shocking when an early episode is placed beside a recent one.

Sean Murray was born November 15, 1977.

He was in his twenties during the show’s earliest period.

By 2026, he was approaching fifty.

The “Probie” had become one of the people new agents could look toward for experience.

Brian Dietzen underwent a similar transformation.

Jimmy Palmer entered the series as Ducky’s awkward assistant.

He was initially used heavily for comic relief.

Palmer could become nervous at precisely the wrong moment.

He sometimes said things he probably should have kept to himself.

Ducky patiently guided him.

Then Palmer grew up.

He became more confident.

He became a husband.

A father.

Eventually, he became NCIS chief medical examiner.

One of Palmer’s most painful storylines came when his wife, Breena, died during the COVID-19 pandemic.

The loss occurred largely away from the audience.

What viewers saw was Palmer trying to continue living afterward.

Dietzen transformed a character who had once been primarily funny into one of the emotional centers of the series.

Then David McCallum died.

Suddenly, the relationship between Palmer and Ducky carried an entirely new meaning.

The student had truly become the successor.

Lauren Holly’s Jenny Shepard had a very different journey.

Holly was already famous before joining NCIS.

Audiences knew her from Picket Fences, Dumb and Dumber and numerous other projects.

Jenny became NCIS director.

She also had a romantic history with Gibbs.

That made their professional relationship complicated from the beginning.

Jenny could challenge Gibbs in ways few characters could.

She had authority over him.

But she also knew the man behind the badge.

Eventually, the series revealed that Jenny was seriously ill.

Her final storyline ended violently.

She confronted armed attackers at a diner and was killed.

It was another reminder that NCIS was willing to remove major characters permanently.

Lauren Holly, however, continued acting after leaving the series.

Jenny’s death opened the door for another long-serving character.

Leon Vance.

Rocky Carroll played Vance.

At first, viewers did not necessarily trust him.

Vance challenged Gibbs.

He operated secretively.

His motives could be difficult to understand.

Eventually, however, he became part of the family.

His own life was devastated when his wife, Jackie, was killed.

That storyline revealed a more vulnerable side of the normally controlled director.

Vance’s long tenure demonstrated another pattern within NCIS.

New characters were frequently treated with suspicion because audiences loved the people they replaced.

Given enough time, some of those replacements became beloved themselves.

The same happened with Ziva.

The same happened with Bishop.

And eventually, the same challenge faced Alden Parker.

Before Parker, however, another enormous loss occurred.

Gibbs left.

Replacing Gibbs directly would have been almost impossible.

So the series wisely did something else.

Gary Cole’s Alden Parker was not turned into another Leroy Jethro Gibbs.

Parker had a different personality.

Different habits.

Different leadership instincts.

He did not attempt to imitate Harmon’s performance.

That allowed the series to move forward without pretending nothing had changed.

Another major transition came after Ziva.

Emily Wickersham joined as Eleanor Bishop.

Bishop entered with an analytical intelligence background.

She was quirky and initially very different from the agents around her.

Over time, she became a field operative capable of handling dangerous assignments.

Her relationship with Nick Torres gradually developed romantic tension.

Then Bishop left for an undercover assignment.

Once again, NCIS refused to provide the easy romantic conclusion audiences might have expected.

Wilmer Valderrama’s Nick Torres had joined the team after Tony’s departure.

Valderrama was already famous as Fez from That ’70s Show.

Torres was almost the opposite of that comedic role.

He was a highly experienced undercover operative.

He distrusted emotional dependence.

He was accustomed to working alone.

Then he joined NCIS and discovered the same thing almost everyone discovered eventually.

The team becomes family.

Diona Reasonover faced another difficult challenge when she became Kasie Hines.

Nobody could simply replace Abby Sciuto.

Trying to create another Abby would have failed immediately.

Kasie therefore developed her own personality.

She became the laboratory’s forensic scientist without becoming a copy of the woman who had occupied that space for fifteen seasons.

Katrina Law’s Jessica Knight represented another generation.

By then, the NCIS audience had already survived so many cast changes that change itself had become part of the show’s identity.

But some losses happened outside the fictional world.

Ralph Waite played Jackson Gibbs, Jethro’s father.

Older television audiences already loved Waite as John Walton Sr. from The Waltons.

His appearances on NCIS revealed something audiences rarely saw.

Gibbs as a son.

Jackson and Jethro loved each other, but their relationship carried years of complicated history.

Around Jackson, Gibbs could not simply be the intimidating boss.

He was someone’s child.

Ralph Waite died in 2014 at age 85.

The series incorporated that real loss into Gibbs’ story.

Jackson died as well.

Gibbs returned home and confronted another painful piece of his past.

Waite was not the only performer associated with NCIS who later died.

The enormous guest cast accumulated hundreds of actors over more than two decades.

Some were already veterans when they appeared.

Others died unexpectedly young.

Annie Wersching appeared on NCIS before becoming widely recognized through shows including 24, Bosch, Timeless and Star Trek: Picard.

She died from cancer in January 2023.

She was only 45.

René Auberjonois also appeared within the NCIS world.

He had already built an extraordinary career through theater, film and television, including unforgettable work on Benson and Star Trek: Deep Space Nine.

He died in 2019 at age 79.

Gregory Itzin, remembered by many viewers as President Charles Logan on 24, also appeared on NCIS during his prolific career.

He died in 2022 at age 74.

Ravil Isyanov, a veteran character actor whose face appeared across numerous American television dramas and films, died in 2021.

Vachik Mangassarian, who appeared within the wider NCIS franchise, died in 2022.

Heath Freeman, another actor who appeared on the series, died in 2021 at only 41.

These performers were not all members of Gibbs’ permanent team.

But after hundreds of episodes, the NCIS universe had accumulated an enormous acting family.

Time inevitably began taking members of it away.

That is what makes revisiting the earliest episodes so strange.

Everyone seems frozen.

Tony is still teasing Kate.

Kate is still rolling her eyes.

Abby is racing around the laboratory.

McGee is still “Probie.”

Palmer is still nervous around Ducky.

Gibbs is still standing at the center of everything.

And Ducky is still talking.

The viewer knows what the characters do not.

Kate will die.

Ziva will arrive.

Tony will fall in love with her without ever finding an easy way to say it.

Ziva will leave.

Tony will discover Tali.

Tony will leave.

Abby will leave.

Bishop will arrive and eventually leave.

Gibbs will walk away.

Palmer will take over the morgue.

McGee will become a veteran.

And David McCallum will eventually die in real life.

That knowledge changes old episodes.

A simple conversation between Ducky and Palmer becomes more emotional.

An argument between Kate and Tony becomes precious because there will never be enough of them.

A Gibbs-and-Abby scene becomes a reminder of an era that cannot be recreated.

Television preserves time in a way ordinary life cannot.

Press play on an episode from 2003 and Mark Harmon is suddenly in his early fifties again.

Michael Weatherly is in his thirties.

Sasha Alexander is thirty.

Pauley Perrette is in her thirties.

Sean Murray looks almost impossibly young.

David McCallum, already the oldest member of the ensemble, somehow appears exactly where he belongs.

Nobody has aged.

Nobody has left.

Nobody has died.

Then the episode ends.

Reality returns.

That may be the saddest part of watching NCIS in 2026.

The series survived almost everything.

It survived Kate’s death.

It survived Ziva leaving.

It survived Tony leaving.

It survived Abby leaving.

It survived Gibbs stepping away.

It survived enormous changes in television itself.

It even survived losing Ducky.

But survival changed the show.

The young characters became veterans.

The assistants became department heads.

The probationary agents became mentors.

The actors who once appeared impossibly energetic grew older alongside the people watching them.

For longtime fans, that passage of time is personal.

Someone who was twenty when NCIS premiered is now in their forties.

Someone who watched the first episodes with their parents may now have children old enough to watch the series.

People who remember Tony calling McGee “Probie” have watched McGee become one of the most experienced people in the building.

That is something few television dramas survive long enough to accomplish.

And perhaps David McCallum represents that passage of time better than anyone.

When NCIS began, he was already a legend from another generation of television.

Then an entirely new generation stopped seeing Illya Kuryakin when they looked at him.

They saw Ducky.

He spent twenty years giving the dead fictional characters their final stories.

Then, eventually, his colleagues had to tell his.

The irony was painfully appropriate.

Ducky always believed the dead should be remembered as people rather than evidence.

The series ultimately treated him the same way.

Not merely as the medical examiner who had occupied the morgue.

Not simply as another departed cast member.

But as part of the family’s history.

That history now stretches across generations.

Some of its original members are gone.

Others have moved on.

Some returned after years away.

And a few remained long enough to become almost unrecognizable from the young actors viewers first met.

That is why looking at the NCIS cast then and now can be surprisingly emotional.

It is not simply about wrinkles, gray hair or changing appearances.

It is about time.

In the earliest episodes, the future is still invisible.

Kate is alive.

Tony has never met Ziva.

McGee has no idea he will spend decades at NCIS.

Palmer does not know he will eventually inherit Ducky’s position.

Gibbs is still running from his past.

Abby still occupies her laboratory.

Ducky is still waiting downstairs.

For one hour, the original family exists again.

Then the credits roll.

And more than two decades have passed.